Story highlights Ukraine's U.N. ambassador vows to not "let the Crimea scenario repeat"

U.S. ambassador accuses Russia of spreading disinformation

"Further escalation" must be stopped, says Russia's U.N. ambassador

Ukrainian President promises punishment for violent protesters

Strong condemnations and accusations were traded Sunday night as the U.N. Security Council held an urgent, previously unscheduled meeting to discuss the worsening crisis in Ukraine.

Speaking first, Oscar Fernandez-Taranco, U.N. assistant secretary-general for political affairs, set the tone for discussions, saying that Ukraine "teeters on the brink.

"However, it is not just Ukraine that will suffer from a scenario where the likelihood of further bloodshed and violent clashes grows by the hour.

"Russia, which shares a large border with Ukraine, as well as the broader European region faces spillover effect of potentially severe consequences. Such scenarios will also have repercussions for the entire international community," he said.

Ukraine and its allies blamed Russia for the unrest, while both sides agreed the situation is dangerous and should not be allowed to get any worse.

Photos: Photos: Crisis in Ukraine Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A man looks at a bullet shell next to a destroyed car after a gunfight between pro-Russian militiamen and Ukrainian forces in Karlivka, Ukraine, on Friday, May 23. Much of Ukraine's unrest has been centered in the Donetsk and Luhansk regions, where separatists have claimed independence from the government in Kiev. Hide Caption 1 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – The body of a pro-Ukrainian militia fighter lies along a road in Karlivka on May 23. Hide Caption 2 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A woman walks past a destroyed car after Ukrainian government forces fired mortar shells during clashes with pro-Russian forces in Slovyansk, Ukraine, on May 23. Hide Caption 3 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A pro-Russian activist carries a ballot box away from a polling station in Donetsk, Ukraine, as he prepares to smash it on May 23. Hide Caption 4 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Local citizens help support a woman at a rally protesting shelling by Ukrainian government forces in the village of Semyonovka, Ukraine, on Thursday, May 22. Hide Caption 5 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Bodies covered with blankets lie in a field near the village of Blahodatne, Ukraine, on May 22, as a Ukrainian soldier smokes next to his armored infantry vehicle. Hide Caption 6 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian soldier rests inside an armored personnel carrier at a checkpoint near Slovyansk on Wednesday, May 21. Hide Caption 7 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Yekaterina Len cries outside her home after it was hit by mortar shells during fighting between pro-Russian separatists and Ukrainian soldiers in Slovyansk on Tuesday, May 20. Hide Caption 8 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian soldier stands guard on the road from Izium, Ukraine, to Slovyansk on Monday, May 19. Hide Caption 9 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A new recruit gets his hair cut at a training camp for the Donbass Battalion, a pro-Ukrainian militia, in the Dnipropetrovsk region of Ukraine on May 19. Hide Caption 10 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian armed militants guard a checkpoint in Slovyansk on May 19, blocking a major highway to Kharkiv. Hide Caption 11 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian militants detain three men on Sunday, May 18, in Kramatorsk, Ukraine. The men are suspected of spying for the Ukrainian government. Hide Caption 12 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A bodyguard of insurgent leader Denis Pushilin stands in front of a statue of Russian revolutionary Vladimir Lenin during a pro-Russia rally in Donetsk on May 18. Hide Caption 13 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian militants guard a checkpoint outside Slovyansk on Saturday, May 17. Hide Caption 14 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Employees of the Ukrainian company Metinvest clear away debris in a government building in Mariupol, Ukraine, on Friday, May 16, after pro-Russian separatists relinquished their hold on it. Hide Caption 15 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian activists argue in Mariupol about how to thwart the upcoming Ukrainian presidential elections. Hide Caption 16 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian gunmen take up positions to fight Ukrainian national troops at a checkpoint outside Slovyansk on Thursday, May 15. Hide Caption 17 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A mortar shell sticks out of the ground at a checkpoint near Slovyansk on May 15. Hide Caption 18 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A man surveys the damage to his home after a mine exploded during an exchange of fire between pro-Russian militants and government troops outside Slovyansk on May 15. Hide Caption 19 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A man examines ballots at a printing house in Kiev, Ukraine, on Wednesday, May 14. The ballots will be used in early presidential voting on May 25. Hide Caption 20 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – People collect mortar shells in front of a burnt-out Ukrainian military vehicle near Oktyabrskoe, Ukraine, on May 14. Hide Caption 21 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Two men collect parts of a Ukrainian armored personnel carrier, destroyed May 14 in what the Ukrainian Defense Ministry called a terrorist attack near Kramatorsk. Hide Caption 22 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A member of a "self-defense" squad smashes a slot machine with a sledgehammer Monday, May 12, at an illegal club in Slovyansk. Hide Caption 23 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – People celebrate with fireworks in Donetsk on May 12 as separatists declared independence for the Donetsk region. Hide Caption 24 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Roman Lyagin, a member of a rebel election commission, shows referendum results to journalists at a May 12 news conference in Donetsk. Pro-Russian separatists staged the referendum asking residents in the Donetsk and Luhansk regions whether they should declare independence from Ukraine. Hide Caption 25 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – An armed pro-Russian separatist takes up a position near Slovyansk on May 12. Hide Caption 26 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A man with a "self-defense" unit checks people's identification in Slovyansk on Sunday, May 11. Hide Caption 27 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A person leaves a voting booth in Luhansk, Ukraine, on May 11. The Donetsk and Luhansk regions of eastern Ukraine voted on controversial referendums to declare independence from the government in Kiev. Acting Ukrainian President Oleksandr Turchynov called the vote "propagandist farce." Hide Caption 28 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Two men react after Ukrainian national guardsmen open fire on a crowd outside a town hall in Krasnoarmiysk, Ukraine, on May 11. Hide Caption 29 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian woman votes at a polling station in Donetsk on May 11. Hide Caption 30 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainians line up to cast their votes at a polling station in Donetsk on May 11. Hide Caption 31 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A voter casts her ballot in eastern Ukraine's independence referendum in Slovyansk on May 11. Hide Caption 32 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – An armed pro-Russian man sits below a flag of the self-proclaimed Donetsk People's Republic at the barricades on a road leading into Slovyansk on May 11. Hide Caption 33 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Black smoke billows from burning tires used to prevent government troops' armored personnel carriers from passing through in Mariupol on Saturday, May 10. Hide Caption 34 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – The mother of Dmitriy Nikityuk, who died in a fire at a trade union building during riots in Odessa, Ukraine, cries next to his coffin during his funeral on Thursday, May 8. Hide Caption 35 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian soldier keeps guard at a checkpoint near Slovyansk on May 8. Hide Caption 36 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A pro-Russian activist stands with a Russian national flag outside the regional Interior Ministry building in Luhansk on Wednesday, May 7. Hide Caption 37 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian Prime Minister Arseniy Yatsenyuk, right, inspects an armored personnel carrier in Slovyansk on May 7. Hide Caption 38 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – An armed pro-Russian separatist takes a position by the railway lines near Slovyansk on Tuesday, May 6. Hide Caption 39 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A relative mourns by the body of 17-year-old Vadim Papura during a service in Odessa on May 6. Papura died after jumping out of a burning trade union building during riots on May 2. Hide Caption 40 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A pro-Russian gunman holds his weapon while guarding the local administration building in Slovyansk on May 6. Hide Caption 41 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian supporters lead blindfolded men in front of the regional administration building in Donetsk on Monday, May 5. Hide Caption 42 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian policemen check documents at a checkpoint near the northeastern city of Izium on May 5. Hide Caption 43 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian soldiers stand at a checkpoint near Slovyansk on May 5. Hide Caption 44 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian Cossacks sit outside the regional administration building in Donetsk on May 5. Hide Caption 45 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian militants who were arrested during a Ukrainian unity rally are greeted on Sunday, May 4, after being freed by police in Odessa. The men released Sunday had been detained after bloody clashes in Odessa, which ended in a deadly blaze. Forty-six people were killed in the bloodshed. Hide Caption 46 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A pro-Russian militant reacts after being freed on May 4 in Odessa. Hide Caption 47 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian militants clash with police as they storm the police station in Odessa on May 4. Hide Caption 48 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – An Orthodox priest, in front of the administration building in Donetsk, blesses a pro-Russian activist May 4 as people gather to honor the memory of fallen comrades in Odessa. Hide Caption 49 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Red carnations are left inside the burned trade union building in Odessa on May 4. Flowers, candles and photos of the dead piled up outside the charred building, a day after brutal clashes and the fire claimed 46 lives. Hide Caption 50 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian protesters light candles in Donetsk on Saturday, May 3, to honor the memory of fallen comrades in Odessa. Hide Caption 51 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A woman cries in front of the burned trade union building in Odessa on May 3. Hide Caption 52 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A man walks past burning tires near Kramatorsk on May 3. Hide Caption 53 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian activists beat a pro-Ukraine supporter trying to save the Ukrainian flag that was removed from a flagpole outside the burned trade union building in Odessa. Hide Caption 54 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian protesters gather in Donetsk to honor the memory of comrades who died in Odessa. Hide Caption 55 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A portrait of Bolshevik leader Vladimir Lenin is part of a barricade in the center of Slovyansk on May 3. The city has become the focus of an armed pro-Russian, anti-government insurgency that aspires to give the eastern regions of Ukraine full autonomy. Hide Caption 56 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A pro-Russian activist sits in front of policemen guarding the burned trade union building in Odessa on May 3. Hide Caption 57 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – People lay flowers and candles at the burned trade union building in Odessa on May 3. Hide Caption 58 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian soldiers arrive to reinforce a checkpoint that troops seized Friday, May 2, in Andreevka, a village near Slovyansk. Two helicopters were downed Friday as Ukrainian security forces tried to dislodge pro-Russian separatists from Slovyansk, Ukraine's Defense Ministry said. Hide Caption 59 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Police take cover under shields as pro-Russian activists storm the prosecutor's office in Donetsk on Thursday, May 1. Eastern Ukraine was a heartland of support for President Viktor Yanukovych, who was ousted in February. Hide Caption 60 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A pro-Russian activist is wounded after storming the prosecutor's office in Donetsk and clashing with riot police on May 1. Hide Caption 61 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian activists storm the prosecutor's office in Donetsk on May 1. Police fired tear gas and stun grenades in an effort to disperse the activists. Hide Caption 62 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – An injured Pro-Russian activist speaks with an armed protester during clashes with police in front of the regional administration building in Donetsk on May 1. Hide Caption 63 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian activists storm an administration building in the center of Luhansk on Tuesday, April 29. Hide Caption 64 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russia militants, armed with baseball bats and iron bars, hold flares as they attack people marching for national unity in Donetsk on Monday, April 28. Hide Caption 65 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Detained observers from the Organization for Security and Co-operation in Europe arrive to take part in a news conference Sunday, April 27, in Slovyansk. Vyacheslav Ponomarev, the self-declared mayor of Slovyansk, referred to the observers as "prisoners of war." Hide Caption 66 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian troops stand guard behind a barricade made of sandbags at a checkpoint about 30 kilometers (20 miles) from Slovyansk on April 27. Hide Caption 67 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Relatives and friends of a man killed in a gunfight participate in his funeral ceremony in Slovyansk on Saturday, April 26. Hide Caption 68 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – U.S. troops arrive at an air force base near Siauliai Zuokniai, Lithuania, on April 26. The United States is conducting military exercises in Poland, Latvia, Estonia and Lithuania. The exercises are, in part, a response to the ongoing instability in Ukraine. Hide Caption 69 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian government troops in armored vehicles travel on a country road outside the town of Svyitohirsk in eastern Ukraine on April 26. Hide Caption 70 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russia armed militants inspect a truck near Slovyansk on Friday, April 25. Russian Foreign Minister Sergey Lavrov has accused the West of plotting to control Ukraine, and he said the pro-Russia insurgents in the southeast would lay down their arms only if the Ukrainian government clears out the Maidan protest camp in the capital, Kiev. Hide Caption 71 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russia militants keep records of their duty in Slovyansk on April 25. Hide Caption 72 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian troops take position near burning tires at a pro-Russian checkpoint in Slovyansk on Thursday, April 24. Hide Caption 73 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian special forces take position at an abandoned roadblock in Slovyansk on April 24. Hide Caption 74 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian special forces member takes position in Slovyansk. Hide Caption 75 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Cossacks carry a coffin into a church in Slovyansk on Tuesday, April 22, during a funeral for men killed in a gunfight at a checkpoint two days before. Hide Caption 76 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – U.S. Vice President Joe Biden, left, talks with Ukrainian Prime Minister Arseniy Yatsenyuk during a meeting in Kiev on April 22. Hide Caption 77 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – An armed pro-Russian man stands on a street in Slovyansk on Monday, April 21. Hide Caption 78 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Demonstrators attend a pro-Russian rally outside the secret service building in Luhansk on April 21. Hide Caption 79 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Cars are burned out after an attack at a roadblock in Slovyansk on Sunday, April 20. Hide Caption 80 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A resident inspects burnt-out cars at a roadblock on April 20. Hide Caption 81 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A pro-Russian militant is seen at the roadblock near Slovyansk on April 20. Hide Caption 82 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Armed pro-Russian militants stand guard at a roadblock near Slovyansk on April 20. Hide Caption 83 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A masked man stands guard outside a regional administration building seized by pro-Russian separatists in Slovyansk on Friday, April 18. Hide Caption 84 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – People walk around barricades April 18 set up at the regional administration building that was seized earlier in Donetsk. Hide Caption 85 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Russian President Vladimir Putin speaks to the media after a nationally televised question-and-answer session in Moscow on Thursday, April 17. Putin denied that Russian forces are involved in the unrest in eastern Ukraine, though he did say for the first time that Russians were active in Crimea before the peninsula voted to join the country. Hide Caption 86 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian riot police officers stand guard during a pro-Ukrainian demonstration in Donetsk on April 17. Hide Caption 87 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Masked pro-Russian protesters stand guard in front of the city hall in Mariupol on April 17. Hide Caption 88 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – U.S. Secretary of State John Kerry reaches out to shake hands with Russian Foreign Minister Sergey Lavrov at the start of a bilateral meeting to discuss the ongoing situation in Ukraine. The meeting took place April 17 in Geneva, Switzerland. Hide Caption 89 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A masked gunman stands guard near tanks in Slovyansk on Wednesday, April 16. Hide Caption 90 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian helicopter flies over a column of Ukrainian Army combat vehicles on the way to Kramatorsk on April 16. Hide Caption 91 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A masked pro-Russian gunman guards combat vehicles parked in downtown Slovyansk on April 16. Hide Caption 92 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A man talks with Ukrainian soldiers as they are blocked by people on their way to Kramatorsk. Hide Caption 93 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian soldiers sit atop combat vehicles on their way to Kramatorsk. Hide Caption 94 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian Gen. Vasily Krutov is surrounded by protesters after addressing the crowd outside an airfield in Kramatorsk on Tuesday, April 15. Hide Caption 95 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian activists guard a barricade April 15 outside the regional police building that they seized in Slovyansk. Hide Caption 96 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian troops receive munitions at a field on the outskirts of Izium on April 15. Hide Caption 97 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Armed pro-Russian activists stand guard on top of a Ukrainian regional administration building in Slovyansk on Monday, April 14. Hide Caption 98 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A pro-Russian activist carries a shield during the mass storming of a police station in Horlivka, Ukraine, on April 14. Hide Caption 99 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Russian supporters attend a rally in front of the security service building occupied by pro-Russian activists in Luhansk on April 14. Hide Caption 100 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A man places a Russian flag over a police station after storming the building in Horlivka on April 14. Hide Caption 101 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Men besiege the police station in Horlivka. Hide Caption 102 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – The Horlivka police station burns on April 14. Hide Caption 103 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian police officer receives medical care after being attacked at the police station in Horlivka on April 14. Hide Caption 104 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian supporters beat a pro-Ukrainian activist during a rally in Kharkiv on Sunday, April 13. Hide Caption 105 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian activists escort a man outside the secret service building in Luhansk on April 13. Hide Caption 106 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian protesters guard a barricade in Slovyansk on April 13 outside a regional police building seized by armed separatists the day before. Hide Caption 107 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Armed pro-Russian activists carrying riot shields occupy a police station in Slovyansk on April 12. Hide Caption 108 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A group of pro-Russian activists warm themselves by a fire Friday, April 11, in front of a Ukrainian Security Service office in Luhansk. Hide Caption 109 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian Prime Minister Arseniy Yatsenyuk speaks April 11 during his meeting with regional leaders in Donetsk. Yatsenyuk flew into Donetsk, where pro-Russian separatists occupied the regional administration building and called for a referendum. Hide Caption 110 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian young men look over the fence of a military recruitment office in Donetsk on Thursday, April 10. Hide Caption 111 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Armed pro-Russian protesters occupy the Security Service building in Luhansk on April 10. Hide Caption 112 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Members of the self-proclaimed government the "Donetsk Republic" vote April 10 during a meeting at the seized regional administration building in Donetsk. Hide Caption 113 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian lawmakers from different parties scuffle during a Parliament session in Kiev on Tuesday, April 8. Hide Caption 114 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Workers clean up on April 8 after pro-Russian separatists and police clashed overnight in Kharkiv. Hide Caption 115 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian protesters burn tires near a regional administration building in Kharkiv after police cleared the building on Monday, April 7. Hide Caption 116 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A masked man stands on top of a barricade at the regional administration building in Donetsk on April 7. Hide Caption 117 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Protesters wave a Russian flag as they storm the regional administration building in Donetsk on Sunday, April 6. Protesters seized state buildings in several east Ukrainian cities, prompting accusations from Kiev that Moscow is trying to "dismember" the country. Hide Caption 118 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian protesters clash with police as they try to occupy a regional administration building in Donetsk on April 6. Hide Caption 119 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian activists hold a rally in front of a Ukrainian Security Service office in Luhansk on April 6. Hide Caption 120 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A young demonstrator with his mouth covered by a Russian flag attends a pro-Russia rally outside the regional government administration building in Donetsk on Saturday, April 5. Hide Caption 121 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian soldier guards a road not far from Prokhody, a village near the Russian border, on April 5. Ukrainian and Western officials have voiced alarm about Russia's reported military buildup on Ukraine's eastern border. Hide Caption 122 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian cadets at the Higher Naval School embrace a friend who has decided to stay in the school during a departure ceremony in Sevastopol, Crimea, on Friday, April 4. Some 120 cadets who refused to take Russian citizenship left the school to return to Ukraine. Hide Caption 123 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Soviet military veterans take part in a flower-laying ceremony at the Soviet-era World War II memorial in Sevastopol on Thursday, April 3. Hide Caption 124 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian soldiers conduct a training session on the Desna military shooting range northeast of Kiev on Wednesday, April 2. Hide Caption 125 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Russian soldiers prepare for diving training in front of a Tarantul-III class missile boat Tuesday, April 1, in Sevastopol. Hide Caption 126 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – People pass by barricades near the Dnipro Hotel in Kiev on April 1. Hide Caption 127 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – People walk past a train loaded with Russian tanks Monday, March 31, in the Gvardeyskoe railway station near Simferopol, Crimea. Hide Caption 128 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Russian solder sits in a tank at the Ostryakovo railway station, not far from Simferopol on March 31. Hide Caption 129 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Russian Prime Minister Dmitry Medvedev speaks about the economic development of Crimea during a meeting March 31 in Simferopol. Hide Caption 130 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Members of the Ukrainian National Guard take part in military exercises on a shooting range near Kiev on March 31. Hide Caption 131 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A woman cries Sunday, March 30, during a gathering to honor those who were killed during protests in Kiev's Independence Square. Hide Caption 132 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A woman and child walk past a line of police officers during a rally in Kharkiv on March 30. Hide Caption 133 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian soldiers take part in a training exercise at a military base in Donetsk on Saturday, March 29. Hide Caption 134 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Demonstrators protest Friday, March 28, in Kiev, displaying police vehicles they seized during earlier clashes with authorities. Hide Caption 135 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Members of the Right Sector group block the Ukrainian parliament building in Kiev on Thursday, March 27. Activists called for Interior Minister Arsen Avakov to step down after the recent killing of radical nationalist leader Oleksandr Muzychko , who died during a police operation to detain him. Muzychko and the Right Sector are credited with playing a lead role in the protests that toppled Ukrainian President Victor Yanukovych. Hide Caption 136 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian tanks are transported from their base in Perevalne, Crimea, on Wednesday, March 26. After Russian troops seized most of Ukraine's bases in Crimea, interim Ukrainian President Oleksandr Turchynov ordered the withdrawal of armed forces from the Black Sea peninsula, citing Russian threats to the lives of military staff and their families. Hide Caption 137 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian marines wave as they leave a base in Feodosia, Crimea, on Tuesday, March 25. Hide Caption 138 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Russian sailors stand on the deck of the corvette ship Suzdalets in the bay of Sevastopol on March 25. Hide Caption 139 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian militia members remove a resident as Russian troops assault the Belbek air base, outside Sevastopol, on Saturday, March 22. After its annexation of Crimea, Russian forces have consolidated their control of the region. Hide Caption 140 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Soldiers in unmarked uniforms sit atop an armored personnel carrier at the gate of the Belbek air base on March 22. Hide Caption 141 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Russian sailor holds the Russian Navy's St. Andrew's flag while standing on the bow of the surrendered Ukrainian submarine Zaporozhye on March 22 in Sevastopol. Hide Caption 142 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Russian President Vladimir Putin signs the final decree completing the annexation of Crimea on Friday, March 21, as Upper House Speaker Valentina Matviyenko, left, and State Duma Speaker Sergei Naryshkin watch. Hide Caption 143 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian serviceman leaves a Ukrainian military unit that Russian soldiers took control of in Perevalne on March 21. Hide Caption 144 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian border guards run during training at a military camp in Alekseyevka, Ukraine, on March 21. Hide Caption 145 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Russian soldiers patrol the area surrounding a Ukrainian military unit in Perevalne on Thursday, March 20. Hide Caption 146 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian protesters remove the gate to the Ukrainian navy headquarters as Russian troops stand guard in Sevastopol on Wednesday, March 19. Hide Caption 147 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russian forces walk inside the Ukrainian navy headquarters in Sevastopol on March 19. Hide Caption 148 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A member of pro-Russian forces takes down a Ukrainian flag at the Ukrainian navy headquarters in Sevastopol on March 19. Hide Caption 149 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Alexander Vitko, chief of the Russian Black Sea Fleet, leaves the Ukrainian navy headquarters in Sevastopol after pro-Russian forces took it over on March 19. Hide Caption 150 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Russian flag waves as workers install a new sign on a parliament building in Simferopol, Crimea's capital, on March 19. Hide Caption 151 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Russian military personnel surround a Ukrainian military base in Perevalne on March 19. Hide Caption 152 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Nameplates on the front of the Crimean parliament building get removed Tuesday, March 18, in Simferopol. Hide Caption 153 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – From left, Crimean Prime Minister Sergey Aksyonov; Vladimir Konstantinov, speaker of the Crimean parliament; Russian President Vladimir Putin; and Alexei Chaly, the new de facto mayor of Sevastopol, join hands in Moscow on March 18 after signing a treaty to make Crimea part of Russia. Hide Caption 154 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Demonstrators hold a Crimean flag at Lenin Square in Simferopol on March 18. Hide Caption 155 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian soldiers stand guard at a checkpoint near Strilkove, Ukraine, close to Crimea on Monday, March 17. Hide Caption 156 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Former boxer and Ukrainian politician Vitali Klitschko addresses reporters in Kiev on March 17. Hide Caption 157 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Ukrainian troops stand guard in front of the Ukrainian Parliament building in Kiev on March 17. Hide Caption 158 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian man applies for the National Guard at a mobile recruitment center in Kiev on March 17. Hide Caption 159 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Civilians walk past riot police in Simferopol on March 17. Hide Caption 160 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian soldier stands on top of an armored vehicle at a military camp near the village of Michurino, Ukraine, on March 17. Hide Caption 161 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Policemen stand guard outside the regional state administration building in Donetsk during a rally by pro-Russia activists March 17. Hide Caption 162 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Armed soldiers stand guard outside a Ukrainian military base in Perevalne on March 17. Hide Caption 163 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A man holds a Crimean flag as he stands in front of the Crimean parliament building in Simferopol on March 17. Hide Caption 164 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Crimeans holding Russian flags celebrate in front of the parliament building in Simferopol on Sunday, March 16. Hide Caption 165 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A Ukrainian police officer tries to shield himself from a road block thrown by pro-Russia supporters in Kharkiv on March 16. Hide Caption 166 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – Pro-Russia demonstrators storm the prosecutor general's office during a rally in Donetsk on March 16. Hide Caption 167 of 168 Photos: Photos: Crisis in Ukraine Crisis in Ukraine – A woman leaves a voting booth in Sevastopol on March 16. See the crisis in Ukraine before Crimea voted Hide Caption 168 of 168

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"Further escalation of this must be swiftly stopped," said Vitaly Churkin, the Russian ambassador to the United Nations.

"It is the West that will determine the opportunity to avoid civil war in Ukraine," he added, calling for national dialogue.

Samantha Power, the U.S. ambassador to the United Nations, accused Russia of spreading disinformation and inciting instability.

"The human stakes of what is happening in Ukraine are extremely high. The lives of innocent civilians are at risk yet we are being bombarded by Russian disinformation and propaganda, while the Ukrainians are being confronted by incitement and violence," she said.

Power added: "This instability was written and choreographed in and by Russia."

Ukraine's U.N. Ambassador Yuriy Sergeyev vowed not "to let the Crimea scenario repeat in eastern Ukraine," stressing that the government is readying a counterinsurgency plan to strike the "armed terrorists."

"We demand to leave us in peace," Sergeyev said. "It's really the final warning cry."

The meeting came the same day that Ukraine acting President Oleksandr Turchynov issued a promise of amnesty for pro-Russia separatists in eastern Ukraine but warned that anyone who continues to support the takeover of government buildings would be held responsible for their actions.

The acting President added a warning to "terrorists" who did not comply, saying they would be subject to an army anti-terrorism operation if they did not comply by 2 a.m. ET Monday. Similar deadlines have been set and allowed to pass with no consequence.

"We'll not allow any repetition of the Crimean scenario in the east of Ukraine. I have signed a decree that would allow those who did not shoot at our officers to lay down their arms and leave the occupied buildings by Monday morning without fear of being prosecuted," he told a national television audience, according to a CNN translation.

Turchynov added that anyone who supports violence will be punished.

"We are ready to consider a significant expansion of regional powers of all regions and the wider reform of local self-government. However, all those supporting aggressors and occupiers in an armed struggle against our country will not escape punishment and will be prosecuted," he said.

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Ukraine puts blame on Russia

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Turchynov said Russia was responsible for bloodshed; at least one Ukrainian soldier was killed in clashes between pro-Ukrainian crowds and pro-Russian separatists, a high-level source in Ukraine's Security Services told CNN.

Russian Foreign Minister Sergey Lavrov tweeted Sunday that Ukrainian authorities must "stop war against their people" and asked the U.N. Security Council and the Organization for Security and Cooperation in Europe to give "urgent attention" to the crisis in eastern Ukraine.

Earlier, Ukrainian officials placed blame for unrest in the eastern section of their country squarely on their neighbors in Russia in a written statement Sunday from Kiev.

The new Ukrainian government said the security operations were launched against terrorists who are attempting to "destroy our country."

"In the eastern regions of Ukraine, the Russian special service and saboteurs embarked on the large-scale separatist operations to seize power, destabilize the situation threatening the lives of citizens of Ukraine, as well as the separation of the regions of our country," the Foreign Ministry said.

Giving no further details, it also said it had "concrete evidence of Russian special service involvement" in the pro-Russian protests and storming of buildings in the east in recent days and would present it at an international meeting on the Ukraine crisis on Thursday.

Ukrainian security forces launched an operation Sunday to clear pro-Russian separatists from a police headquarters in the eastern city of Slaviansk, officials said.

However, a CNN crew in the city saw no sign of a large presence of Ukrainian security forces -- with the exception of a single police car and a helicopter flying above -- nor any confrontation with the occupiers.

Gunmen dressed in camouflage had stormed and seized the police building a day earlier in Slaviansk, a town about 100 miles from the Russian border, and set up barricades around it.

'Sanctions can bite'

Power, the U.S. ambassador to the United Nations, said the attacks in Slaviansk were "professional" and "coordinated" -- similar to Russia's incursion into the Crimean Peninsula last month.

The United States is prepared to step up sanctions against Russia if the recent actions in Ukraine continue, she said Sunday. Power said told "This Week" the latest events in Ukraine bore "the telltale signs of Moscow's involvement."

"I think we've seen that the sanctions can bite. And if actions like the kind that we've seen over the last few days continue, you're going to see a ramping up of those sanctions," she said.

The unrest is the latest show of spiraling anger in eastern Ukraine, which has a large Russian-speaking population. The region was the support base for pro-Moscow former President Viktor Yanukovych, who was ousted in February after months of protests in Kiev.

Speaking Sunday to reporters in Russia, Yanukovych said the Ukraine is in a new situation now that blood was shed.

"Ukraine made the first step toward civil war. The Kiev gang decided and ordered to use force and dispatched the military forces against the population of southeast Ukraine," he said, state-run Russia-24 TV reported.

Yanukovych accused the United States of dictating to the government in Kiev what to do, claiming that CIA Director John Brennan "effectively sanctioned the use of arms and bloodshed and therefore the United States should be held responsible for starting a civil war in Ukraine."

CIA spokesman Dean Boyd declined to comment on Brennan's travel itinerary.

"But the claim that Director Brennan encouraged Ukrainian authorities to conduct tactical operations inside Ukraine is completely false. Like other senior U.S. officials, Director Brennan strongly believes that a diplomatic solution is the only way to resolve the crisis between Russia and Ukraine," the spokesman said.

Troops massed on eastern border

Kiev's fragile new government and the West accuse Russia of destabilizing the region as a pretext to potentially send in troops to protect the local Russian-speaking population.

NATO says Russian armed forces are massing on Ukraine's eastern border, while Moscow says they are merely carrying out military exercises.

In Kharkiv, Ukraine's second most populous city, police outside City Hall offered no resistance when protesters took over the building Sunday afternoon, according to a witness. It is not clear why the police stepped aside for protesters.

Russian and local Ukrainian media reported that pro-Russian demonstrators had seized the city hall in Mariupol, in the southeast, with no violence. Some showed pictures of Russian flags in the city. The reports could not immediately be independently confirmed.

Distrust among the population in the region grew as political power in the national government shifted rapidly in a pro-Western direction. A short time later, pro-Russian elements occupied the Black Sea peninsula of Crimea, which Russia quickly annexed. Since then, pro-Russian protesters have taken to the streets in eastern Ukrainian regions and in some cases stormed and occupied buildings.

EU foreign minister to meet

The United States has accused Russia of fomenting the separatist unrest in its neighbor as a pretext for military intervention.

U.S. Secretary of State John Kerry spoke by phone with Lavrov, his Russian counterpart, on Saturday, expressing "strong concern that attacks today by armed militants in eastern Ukraine were orchestrated and synchronized, similar to previous attacks in eastern Ukraine and Crimea," a senior State Department official said.

The official said Kerry warned Lavrov there would be "additional consequences" if Russia did not take steps to de-escalate the situation in eastern Ukraine and move its troops back from its border.

The official also noted that militants involved in Saturday's unrest in eastern Ukraine "were equipped with specialized Russian weapons and the same uniforms as those worn by the Russian forces that invaded Crimea."

NATO described the appearance in eastern Ukraine of men with specialized Russian weapons and identical uniforms without insignia -- as previously seen in Crimea -- as a "grave development."

European Union Foreign Policy Chief Catherine Ashton is to meet this week with foreign ministers from the United States, Russia and Ukraine in Switzerland to discuss efforts to de-escalate the situation.

In a written statement, she urged Moscow "to call back its troops from the Ukrainian border and to cease any further actions aimed at destabilising Ukraine."

EU foreign ministers will meet in Luxembourg on Monday to discuss the crisis.