Donetsk, Ukraine (CNN) Diplomats were left scrambling Tuesday as a truce between the government in Ukraine and pro-Russian separatists was falling apart.

The U.N. Security Council unanimously voted, 15-0, to approve a resolution calling on all parties to abide by the ceasefire, which is proving to have more pull on paper than on the ground.

Five more Ukrainian service members have been killed in the past 24 hours, Ukraine's Defense Ministry said Tuesday, the same day as the U.N. vote.

Council members issued a statement expressing "grave concern at the continued fighting in and around Debaltseve, Ukraine, which has resulted in numerous civilian casualties." The members asked for detainees to be treated "humanely."

"We've gotten used to living in an upside down world with respect to Ukraine. Russia speaks of peace and then fuels conflict. Russia signs agreements and then does everything within its power to undermine them," Samantha Power, U.S. ambassador to the United Nations, told council members.

"We are caught in a deadly feedback loop. International leaders engage in rigorous exhaustive negotiations to get Russia to commit to peace ... yet Russia's commitments have no bearing on the actions of its soldiers and the separatists they back on the ground," she said.

For its part, Russia continues to urge dialogue on political and constitutional issues.

"Since the very start of the crisis, Russia has actively called for a peaceful settlement," Vitaly Churkin, Russia's ambassador, told council members.

On Monday, Ukrainian Defense spokesman Andriy Lysenko reported five deaths from the previous day and at least 129 violations of the ceasefire since it went into effect at midnight Saturday.

And there are more signs that the international efforts to stop the bloodshed are failing.

Violence flares in hotly contested city

Heavy clashes broke out Tuesday in Debaltseve, but both the Ukrainian military and pro-Russian separatists say they are not backing down.

Photos: Crisis in Ukraine Photos: Crisis in Ukraine Ukrainian security forces patrol in the village of Bobrovyshche on July 14, 2015. More than 6,400 people have been killed in the conflict in Ukraine since April 2014, the United Nations says. Hide Caption 1 of 49 Photos: Crisis in Ukraine Ukrainian security forces on the lookout in Bobrovyshche on July 14. The country's troops face daily attacks from Russian-backed separatists despite a ceasefire being in place. Hide Caption 2 of 49 Photos: Crisis in Ukraine A man with a machine gun is among the Ukrainian troops standing guard in Krimskoe town of Luhansk, Ukraine, on June 25. Hide Caption 3 of 49 Photos: Crisis in Ukraine Shelling between Ukrainian troops and pro-Russian rebels leaves damage in Donetsk, Ukraine, on Monday, June 1. Hide Caption 4 of 49 Photos: Crisis in Ukraine A Ukrainian serviceman fires a grenade launcher on the front lines near Donetsk on Saturday, May 30. Hide Caption 5 of 49 Photos: Crisis in Ukraine Pro-Russian rebels carry the coffin of prominent separatist commander Alexei Mozgovoi during his funeral in Alchevsk, Ukraine, on Wednesday, May 27. Hide Caption 6 of 49 Photos: Crisis in Ukraine An American soldier, right, trains Ukrainian troops on Tuesday, April 21, near Yavoriv, Ukraine. Operation Fearless Guardian, a six-month training exercise, involves about 300 members of the American 173rd Airborne and about 900 Ukrainian National Guard troops. Hide Caption 7 of 49 Photos: Crisis in Ukraine Residents flee with salvaged belongings during renewed fighting in the Jabunki neighborhood near the airport in Donetsk on Monday, April 13. Hide Caption 8 of 49 Photos: Crisis in Ukraine A mortar round sticks out of the ground near a destroyed tank at a former Ukrainian army checkpoint outside Chornukhyne, Ukraine, on Monday, March 2. Russian-backed separatists had recently overran the area. Hide Caption 9 of 49 Photos: Crisis in Ukraine An instructor of the Ukrainian volunteer Azov Battalion conducts training exercises in Kiev, Ukraine, on Sunday, March 1. Hide Caption 10 of 49 Photos: Crisis in Ukraine A woman makes her way across a bridge destroyed in heavy fighting in Donetsk, Ukraine, on March 1. Hide Caption 11 of 49 Photos: Crisis in Ukraine A volunteer gives humanitarian aid to residents of Popasna, Ukraine, on Saturday, February 28. Hide Caption 12 of 49 Photos: Crisis in Ukraine A Ukrainian serviceman climbs out of a tank at a checkpoint near Horlivka, Ukraine, on Monday, February 23. Hide Caption 13 of 49 Photos: Crisis in Ukraine A member of a Ukrainian military medical unit cries during a ceremony in Artemivsk, Ukraine, on February 23. Four of his comrades were killed near Debaltseve, Ukraine. Hide Caption 14 of 49 Photos: Crisis in Ukraine A man holds a Ukrainian flag as he covers a victim of an explosion in Kharkiv, Ukraine, on Sunday, February 22. The explosion during a peaceful protest left two dead and 15 wounded. Hide Caption 15 of 49 Photos: Crisis in Ukraine Pro-Russian rebels stationed in Horlivka launch missiles on Wednesday, February 18. Hide Caption 16 of 49 Photos: Crisis in Ukraine Pro-Russian separatists take position near Uglegorsk, Ukraine, on February 18. Hide Caption 17 of 49 Photos: Crisis in Ukraine An army ambulance damaged in recent shelling lies by a road near Svitlodarsk, Ukraine, on Sunday, February 15. Hide Caption 18 of 49 Photos: Crisis in Ukraine Ukrainian servicemen play with a soccer ball on a road between Svitlodarsk and Debaltseve on February 15. Hide Caption 19 of 49 Photos: Crisis in Ukraine A woman salvages items February 15 from the rubble of a destroyed clinic where she had worked in Opytne, Ukraine. Hide Caption 20 of 49 Photos: Crisis in Ukraine People carry a refrigerator through a balcony at an apartment building that was damaged in recent shelling in Svitlodarsk on February 15. Hide Caption 21 of 49 Photos: Crisis in Ukraine A recent ceasefire was brokered during marathon talks in Minsk, Belarus. From left, Belarusian President Alexander Lukashenko, Russian President Vladimir Putin, German Chancellor Angela Merkel, French President François Hollande and Ukrainian President Petro Poroshenko gather before negotiations begin on Wednesday, February 11. Hide Caption 22 of 49 Photos: Crisis in Ukraine People stand beside the body of a woman killed during shelling in Kramatorsk, Ukraine, on Tuesday, February 10. Hide Caption 23 of 49 Photos: Crisis in Ukraine A volunteer gets a medical checkup at a military base for pro-Russian rebels February 10 in Donetsk, Ukraine. Hide Caption 24 of 49 Photos: Crisis in Ukraine Ukrainian volunteer fighters and policemen arrest two men in Kiev, Ukraine, on February 9. The men allegedly arrived from Donetsk and were suspected of participating in pro-Russian rebel activities and organizing terrorist attacks in the Ukrainian capital. Hide Caption 25 of 49 Photos: Crisis in Ukraine Residents unload humanitarian aid in Debaltseve on Friday, February 6. Hide Caption 26 of 49 Photos: Crisis in Ukraine A man rides a bicycle in Vuhlehirsk, Ukraine, on February 6. Hide Caption 27 of 49 Photos: Crisis in Ukraine A child waits on a bus to leave Debaltseve on Tuesday, February 3, after increased fighting in the region. Hide Caption 28 of 49 Photos: Crisis in Ukraine A man stands next to his car in Donetsk on Sunday, February 1, after it was destroyed by shelling. Hide Caption 29 of 49 Photos: Crisis in Ukraine The body of a civilian killed during shelling lies on the ground in Donetsk on Friday, January 30. Hide Caption 30 of 49 Photos: Crisis in Ukraine People in Mariupol, Ukraine, pour soil into the grave of a recent shelling victim on Monday, January 26. Hide Caption 31 of 49 Photos: Crisis in Ukraine Ukrainian servicemen prepare ammunition at a position on the front line near Mariupol on January 26. Hide Caption 32 of 49 Photos: Crisis in Ukraine A man injured during shelling in Mariupol sits in an emergency hospital on January 26. Hide Caption 33 of 49 Photos: Crisis in Ukraine A piece of an exploded missile sits lodged in the ground outside an apartment building in the Vostochniy district of Mariupol on Sunday, January 25. Hide Caption 34 of 49 Photos: Crisis in Ukraine A resident walks by a burning building in Mariupol on Saturday, January 24. Hide Caption 35 of 49 Photos: Crisis in Ukraine A pro-Russian rebel takes cover from shelling in the Kievsky district of Donetsk on Thursday, January 22. Hide Caption 36 of 49 Photos: Crisis in Ukraine People in downtown Donetsk react as Ukrainian prisoners of war are handed over by pro-Russian rebels on January 22. Hide Caption 37 of 49 Photos: Crisis in Ukraine A trolleybus is damaged in Donetsk's Lenin District after its station was hit by a shell on January 22. Hide Caption 38 of 49 Photos: Crisis in Ukraine A rebel takes aim while protecting a supply position in the Kievsky district of Donetsk on January 22. Hide Caption 39 of 49 Photos: Crisis in Ukraine Rubble and debris cover the airport in Donetsk on Wednesday, January 21. Hide Caption 40 of 49 Photos: Crisis in Ukraine Hide Caption 41 of 49 Photos: Crisis in Ukraine Vladimir Bovrichev cries next to the body of his 4-year-old son, Artiam, during Artiam's funeral on the outskirts of Donetsk on Tuesday, January 20. The boy was killed during a Ukrainian artillery strike. Hide Caption 42 of 49 Photos: Crisis in Ukraine Women sit in a shelter during a battle in Donetsk on Sunday, January 18. Hide Caption 43 of 49 Photos: Crisis in Ukraine A building hit by Ukrainian artillery is seen in the Voroshilovsky area of Donetsk on January 18. Hide Caption 44 of 49 Photos: Crisis in Ukraine Men from the Azov Volunteer Battalion board a bus in Kiev to join the fight against the rebels on Saturday, January 17. Hide Caption 45 of 49 Photos: Crisis in Ukraine Rebels sit atop a tank at a checkpoint north of Luhansk, Ukraine, on Wednesday, January 14. Hide Caption 46 of 49 Photos: Crisis in Ukraine A Ukrainian soldier looks down from a military truck at the Donetsk airport on Tuesday, January 6. The airport has been the scene of some of the fiercest fighting in eastern Ukraine. Hide Caption 47 of 49 Photos: Crisis in Ukraine Ukrainian President Petro Poroshenko gives a speech as he hands over new military equipment to forces near the city of Ghytomyr, Ukraine, on Monday, January 5. Hide Caption 48 of 49 Photos: Crisis in Ukraine A Ukrainian volunteer fighter fires a machine gun at pro-Russian rebels near the village of Pisky, Ukraine, on Saturday, January 3. Hide Caption 49 of 49

Debaltseve is a crucial city because it a strategic railroad hub in eastern Ukraine.

The separatists have taken over 80% of Debaltseve, said Eduard Basurin, self-declared deputy defense minister of the rebel Donetsk People's Republic.

He also said the separatists now have 60 Ukrainian prisoners of war. CNN cannot independently verify those claims.

Lysenko said Ukrainian troops are holding their positions in Debaltseve in response to the rebels' attacks.

Meeting between warring sides nixed

A planned meeting between Ukrainian officials, pro-Russian separatists and European officials about the shaky ceasefire was canceled after one of the parties failed to show up, a European diplomat familiar with the talks told CNN.

It is not clear what other reasons may have led to the cancellation.

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Members of the Organization for Security and Co-operation in Europe were slated to participate in the meeting.

On Tuesday, Russia and Ukraine reiterated their agreement to let OSCE monitors observe the ceasefire in Debaltseve.

During a phone call with German Chancellor Angela Merkel, Russian President Vladimir Putin and Ukrainian President Petro Poroshenko agreed to "concrete steps" that would provide OSCE monitors access, German government spokesman Steffen Seibert said.

Russia has denied widespread allegations it is supporting the pro-Russian separatists fighting in eastern Ukraine.

Poroshenko has warned that if the separatists do not abide by the ceasefire, he will impose martial law throughout Ukraine's territory.

Civilians caught in the fighting

In the beleaguered village of Shyrokyno, Ukrainian forces struggle to keep control of the territory.

"Right now, only about a third of the village is under our control," a machine gunner named Yury told CNN's Frederik Pleitgen.

Separatists shelled Ukrainian forces with mortars, and both sides skirmished when rebels assaulted government troops with small arms and armored vehicles, said Dmytro Chalov, a spokesman for Ukraine's army in the Mariupol sector. Two Ukrainian security forces were wounded, he said.

Oleg Shiryayev, commander of Ukraine's East Corpus battalion, said the ceasefire "is a farce."

"The fighting is continuing now the way it did before," Shiryayev told Pleitgen. "They continue to attack us, shell us; they use artillery, mortars."

But it's impossible to tell which side is responsible for breaking the ceasefire in Shyrokyno.

To some residents, it doesn't matter.

"The fighting is very heavy. All the windows (of) our house are broken," one woman said. "It is very terrifying. We saved all our lives to buy our house, and now we have nothing."