Story highlights Ukraine rattled by anti-government protests since November

Demonstrations have escalated into violent clashes

Ukraine is split between closer ties with the EU and cooperating more with Russia

First major government concessions made, opposition wants more

Young and old, they have braved the freezing cold for weeks to voice their discontent. Using snow, wood, metal and tires, thousands of protesters have barricaded themselves into a makeshift tent city, paralyzing central Kiev and refusing to leave until their demands are met.

Undeterred by the Ukrainian winter chill, the demonstrators chant day and night, sometimes to the drumbeat of sticks on corrugated iron, and take to the stage to give speeches, demanding the government's ouster and new elections.

For the past few weeks, billowing smoke, large fires, burnt out tires and cars as well as smashed windows of public buildings have become familiar scenes in the snowy city as protests have plunged Ukraine, an eastern European country of 45 million people, into a deep political crisis.

Some of the images beamed around the world have been particularly dramatic -- protesters knocking down a giant statue of the Russian revolutionary leader Vladimir Lenin and hacking it with hammers to loud cheers, explosions reminiscent of a war zone echoing around downtown Kiev, fierce clashes and abuse. One protester, naked aside from his shoes, was seen being kicked and forced onto a police bus.

The battlefield is central Kiev, the power base of an opposition which is demanding change in the former Soviet Union state. The lines have been drawn.

Batons have been raised on both sides -- between the protesters armed with petrol bombs and stones and shielded riot police firing tear gas and rubber bullets -- sometimes resulting in deadly clashes.

Photos: Photos: Ukraine protests turn deadly Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters in Kiev, Ukraine, clash with police in Independence Square on Wednesday, February 19. Thousands of anti-government demonstrators have packed the square since November, when President Viktor Yanukovych reversed a decision on a trade deal with the European Union and instead turned toward Russia. Hide Caption 1 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters clash with police in Kiev on February 19. The unrest in Ukraine intensified after an anti-protest law went into effect in January. Demonstrators took to the streets to protest the law, which was later repealed. Hide Caption 2 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters prepare a barricade in Independence Square on February 19. Hide Caption 3 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Police form a line as the Trade Unions Building burns in Independence Square on February 19. Hide Caption 4 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Police form a barrier in Independence Square on February 19. Hide Caption 5 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters in Kiev throw rocks at riot police in Independence Square on February 19. Hide Caption 6 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Independence Square smolders during protests on February 19. Hide Caption 7 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters walk in the rubble of Independence Square on February 19. Hide Caption 8 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters gather in Kiev on February 19. Hide Caption 9 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester throws a cobblestone at riot police during clashes in Independence Square on February 19. Hide Caption 10 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police officers rest against a column in Independence Square on February 19. Hide Caption 11 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters stand in Independence Square on February 19. Hide Caption 12 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – An injured protester is moved out during clashes with riot police in Kiev on February 19. Hide Caption 13 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester uses a slingshot to throw a rock at riot police February 19 in Kiev. Hide Caption 14 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police line up in Kiev on February 19. Hide Caption 15 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters put on gas masks near the perimeter of Independence Square on February 19. Hide Caption 16 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters brace themselves for more violence in Kiev on February 19. Hide Caption 17 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester throws a stone in Kiev on February 19. Hide Caption 18 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters protect themselves with shields as they clash with police in Kiev on February 19. Hide Caption 19 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – An injured protester waits to be treated in a Kiev monastery, converted into a makeshift hospital, on February 19. Hide Caption 20 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters sleep on the floor inside a Kiev monastery on February 19. Hide Caption 21 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters clash with police in Independence Square on February 19. Hide Caption 22 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester rushes through a broken door in the regional prosecutor's office in Lviv, Ukraine, on February 19. Police said the unrest has spread to western Ukraine, with protesters attacking police and local government offices in a number of regions. Hide Caption 23 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters in Lviv burn papers from a government building on February 19. Hide Caption 24 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester aims a weapon in Kiev on Tuesday, February 18. Hide Caption 25 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police storm Independence Square on February 18. Hide Caption 26 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester runs during clashes with police in Kiev on February 18. Hide Caption 27 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters clash with police in Independence Square on February 18. Hide Caption 28 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters watch clashes in Kiev on February 18. Hide Caption 29 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Violence between police and protesters escalates February 18 in Kiev. Hide Caption 30 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police stand firm in Kiev on February 18. Hide Caption 31 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters burn a car in central Kiev on February 18. Hide Caption 32 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester stands atop a barricade in Kiev on February 18. Hide Caption 33 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters clash with riot police outside Ukraine's parliament in Kiev on February 18. Hide Caption 34 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A rainbow forms over a protester ducking for cover in Kiev on February 18. Hide Caption 35 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police protect themselves during clashes in Kiev on February 18. Hide Caption 36 of 88 Photos: Photos: Ukraine protests turn deadly Hide Caption 37 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester is engulfed in flames while running from the clashes in Kiev on February 18. Hide Caption 38 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police detain a protester in Kiev on February 18. Hide Caption 39 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters invade the main office of the ruling Party of Regions in Kiev on February 18. Hide Caption 40 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police shield themselves during clashes with protesters on February 18. Hide Caption 41 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters throw stones toward riot police in Kiev on February 18. Hide Caption 42 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester holds a Ukrainian flag in Independence Square on Tuesday, February 4. Hide Caption 43 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester smokes a cigarette while standing guard in Kiev on February 4. Hide Caption 44 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters keep an eye on police February 4 as they man a barricade in Kiev. Hide Caption 45 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester is reflected in a broken mirror during protests in Kiev on Monday, February 3. Hide Caption 46 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Opposition supporters warm themselves in Kiev on Saturday, February 1. Hide Caption 47 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester stands on top of barricades in Kiev on Tuesday, January 28. Hide Caption 48 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters sit behind a barricade in Kiev on January 28. Hide Caption 49 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters march in Kiev on Monday, January 27. Activists say they want wide-ranging constitutional reform and a shake-up of the Ukrainian political system. Hide Caption 50 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Police block a street in Kiev on January 27. Hide Caption 51 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A couple try to keep warm near a fire at a barricade in Kiev on January 27. Hide Caption 52 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police block a Kiev street from protesters on January 27. Hide Caption 53 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters stand guard inside the Ukraine Justice Ministry in Kiev on January 27. Demonstrators later left the building because they didn't want to create any difficulties in negotiations between the government and opposition, a protest leader said. Protesters repositioned themselves outside and blocked access to the building, the leader said. Hide Caption 54 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Orthodox priests lead the funeral service for slain protester Mikhail Zhiznevsky in Kiev on Sunday, January 26. Hide Caption 55 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police officers stand in line during anti-government protests in Kiev on Saturday, January 25. Hide Caption 56 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – An Orthodox priest prays during protests on January 25. Hide Caption 57 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Some 10,000 Ukrainians take part in the funeral ceremony of dead protester Yuri Verbytsky in the western city of Lviv on Friday, January 24. Hide Caption 58 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A line of Ukrainian riot police block a road on January 24. Hide Caption 59 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester puts on a gas mask near Dynamo Stadium in Kiev on January 24. Hide Caption 60 of 88 Photos: Photos: Ukraine protests turn deadly Photos: Ukraine protests turn deadly – Ukrainian Oksana Tikhomirova cries as she urges riot police to stop the violence outside a government district in central Kiev on January 24. Hide Caption 61 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Molotov cocktails sit in a basket ready to be used by protesters in Kiev on January 24. Hide Caption 62 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police stand guard near Dynamo Stadium on January 24. Hide Caption 63 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester passes past graffiti that reads "Government for People" in the Ministry of Agricultural Policy building in Kiev on January 24. Hide Caption 64 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A man walks past the wreckage of a car on January 24. Hide Caption 65 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Ukrainian protesters use a huge catapult to throw stones at riot police as tires burn in Kiev on Thursday, January 23. Hide Caption 66 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police officers gather in Kiev on January 23. Hide Caption 67 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Opposition leader Vitali Klitschko, center, addresses protesters near the burning barricades between police and protesters in central Kiev on January 23. Hide Caption 68 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police stand guard near a burnt-out bus covered in icicles in Kiev on January 23. Hide Caption 69 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester walks past burning tires in Kiev on January 23. Hide Caption 70 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester shoots fireworks at police during clashes in Kiev on January 23. Hide Caption 71 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester carries tires toward a fire on January 23. Hide Caption 72 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police officers line up in Kiev during clashes on Wednesday, January 22. Hide Caption 73 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester throws a Molotov cocktail on January 22. Hide Caption 74 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters shoot from behind a shield among burning automobile tires in Kiev on January 22. Hide Caption 75 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Riot police officers gather as they clash with protesters in the center of Kiev on January 22. Hide Caption 76 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester throws a Molotov cocktail during clashes with police in central Kiev. Hide Caption 77 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Ukrainian protesters are seem during a mass action of opposition on Grushevsky Street. Hide Caption 78 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A protester throws a stone in front of a plume of fire and smoke during clashes with police in central Kiev. Hide Caption 79 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Flames leap off a protester during clashes with police on January 22. Hide Caption 80 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A police officer aims his shotgun during clashes with protesters. Hide Caption 81 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Paramedics put a wounded man on a stretcher and into a medical vehicle. Hide Caption 82 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Ukrainian police storm protesters' barricades in Kiev amid violent clashes on January 22. Hide Caption 83 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A European integration supporter is seen in Independence Square. Hide Caption 84 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters are seen in front of burning tires on Grushevsky Street. Hide Caption 85 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A medic treats an injured protester's leg during violent clashes between demonstrators and police. Hide Caption 86 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – A Ukrainian man stands in front of riot police on January 22. Hide Caption 87 of 88 Photos: Photos: Ukraine protests turn deadly Ukraine protests turn deadly – Protesters clash with police in Kiev as snow falls on January 22. Hide Caption 88 of 88

JUST WATCHED Journalist: The people are not satisfied Replay More Videos ... MUST WATCH Journalist: The people are not satisfied 02:46

JUST WATCHED Ukraine protesters demand more Replay More Videos ... MUST WATCH Ukraine protesters demand more 03:31

JUST WATCHED Tymoshenko: Yanukovych still in control Replay More Videos ... MUST WATCH Tymoshenko: Yanukovych still in control 01:21

Photos: Ukraine through the eyes of a protester Photos: Ukraine through the eyes of a protester Ukraine through the eyes of a protester – Ukraine native Freddy UA has been documenting Ukraine protests since they erupted in Kiev in November 2013. He captured these images of the demonstrations on January 24. Hide Caption 1 of 6 Photos: Ukraine through the eyes of a protester Ukraine through the eyes of a protester – Protests started in reaction to the Ukrainian government's failure to sign a trade agreement with the European Union, which many interpreted as a turn away from Europe and toward Russia instead. Hide Caption 2 of 6 Photos: Ukraine through the eyes of a protester Ukraine through the eyes of a protester – Protests continued even after allegations of police brutality and government intimidation. Hide Caption 3 of 6 Photos: Ukraine through the eyes of a protester Ukraine through the eyes of a protester – Despite the cold, protesters started camping out on the streets of Kiev to keep the protesting momentum going, says Freddie UA. Hide Caption 4 of 6 Photos: Ukraine through the eyes of a protester Ukraine through the eyes of a protester – Protesters want a civil discourse with the Ukrainian government without the fear of retaliation, he says. Hide Caption 5 of 6 Photos: Ukraine through the eyes of a protester Ukraine through the eyes of a protester – "For protesters, it looks dangerous because on the other side of the barricades there are still a large number of police who are on duty," says Freddie UA of this image. Hide Caption 6 of 6

But despite a crackdown, demonstrators' morale is high with no sign of their labyrinth of tents, railings and metal barrels that have taken up Kiev's central arteries being dismantled just yet.

It has been two months since the first rattled demonstrators took to the streets, underscoring tensions in a country split between Europe and Russia. But Ukraine's political unrest seems to be worsening by the day -- drawing concern from its neighbors, Western European states and Washington.

Here are some key questions about Ukraine's political unrest.

What sparked the protests?

The protests began in November as a pro-Europe gesture, underscoring the tensions in a country split between pro-European regions in the West and a more Russia-oriented East.

Thousands spilled onto the streets after President Viktor Yanukovych did a U-turn over a trade pact with the European Union that had been years in the making -- favoring closer relations with Russia instead.

Angered by this backpedaling, the demonstrators demanded the EU deal be signed, saying it would strengthen cooperation with the bloc.

Their daily protests soon escalated, drawing parallels to Ukraine's 2004 Orange Revolution, which toppled the government.

But with Ukraine desperately in need of a cash injection, Kiev cited the need for financial assistance if it were to do business with the EU. Yanukovych, in power since 2010, said Ukraine could not afford to sign the deal, alluding to economic pressure from Russia.

Another factor in Yanukovych's decision not to sign the deal is likely to have been the EU's demands that he free from jail former Prime Minister Yulia Tymoshenko, his political opponent. The Orange Revolution that swept him from office in 2004, when he was prime minister, also swept Tymoshenko to power.

Soon afterward, he flew to Moscow where he and President Vladimir Putin announced Russia would buy $15 billion in Ukrainian debt and slash the price Kiev pays for its gas.

While unhappy with that, what inflamed the demonstrators even more, however, was the adoption of a sweeping anti-protest law by the parliament on January 16.

The new law included provisions barring people from wearing helmets and masks to rallies and from setting up tents or sound equipment without prior police permission.

This sparked concerns it could be used to put down demonstrations and deny people the right to free speech -- and clashes soon escalated.

Last week, several people were killed and hundreds of others injured in heavy street fighting.

The epicenter of the protests has been Kiev's central Independence Square, Maidan, but the demonstrators have also blocked other streets and government buildings. On Sunday, they briefly seized the justice ministry.

"The changes that occurred after the Orange Revolution weren't simply deep enough. This time around, it appears that the disenchantment is so strong that there is a genuine opportunity to make a fresh start," said Dalibor Rohac, policy analyst with the Cato Institute's Center for Global Liberty and Prosperity.

"For Ukrainians this is a chance to get on a different trajectory from the one the country has been on for the past 22 years and become eventually a part of prosperous, democratic Europe."

What's being done to try to reach an end to the fighting?

The leaders of three opposition factions have met several times with Yanukovych and a government working group to try to resolve the crisis.

They are former boxer Vitali Klitschko, leader of the Ukrainian Democratic Alliance for Reforms party; Arseniy Yatsenyuk, of the Fatherland party; and Oleh Tiahnybok, of the Freedom party, or Svoboda.

The president's foes have mainly been calling for the government to be dissolved, new elections to be held and for the protest laws to be absolved.

On Saturday, Yanukovych offered a package of concessions under which Yatsenyuk would have become the prime minister and, under the president's offer, been able to dismiss the government.

He also offered Klitschko, a champion boxer known as "Dr. Ironfist," the post of deputy prime minister on humanitarian issues and also agreed to a working group looking at changes to the constitution. But the opposition refused.

"No deal @ua_yanukovych, we're finishing what we started. The people decide our leaders, not you," Yatsenyuk tweeted.

A special parliamentary session also looked at legislation that might provide amnesty for more than 200 people arrested since the demonstrations began in late November. It was adjourned until Wednesday, when lawmakers will continue the debate.

How does the situation affect the rest of the region?

Ukraine is the biggest frontier nation separating Russia and the EU. Once part of the Soviet Union, the country gained its modern Independence in 1991 following the fall of the Berlin Wall.

The West -- the EU, together with the United States -- has been working on its relations with former Soviet bloc countries for more than two decades, with the aim of restoring democratic rule and improving quality of life for Ukrainians.

It views the decision by Ukraine, the largest of the former republics, not to partner up with the EU as bowing to Russian pressure.

Ukraine is something of a pawn between Russia and the West. For the West, the deal would mean its reach would spread further east; by contrast, the Russians see the Ukraine as key to holding on to their turf.

Putin has denied that Moscow is exerting undue influence in Ukraine.

At a long-planned "Russia summit" in Brussels, Belgium, on Tuesday, where Ukraine was high on the agenda, he said: "Russia has always respected, is respecting and will respect the sovereign rights of all the international entities including new states that emerged after breakdown of the Soviet Union."

Putin also said Russia would stick to the loan and energy commitments to Ukraine -- agreed in December -- even if the opposition comes to power.

European Council President Herman van Rompuy told reporters the bloc was ready to move ahead with the planned trade deal, or association agreement that has been at the heart of the crisis, but also urged restraint and said those responsible for violence in Ukraine must be held accountable.

Catherine Ashton, the European Union's foreign policy chief, is due in Kiev on Tuesday.

Ukraine has made an effort to move toward Western ideals when it comes to politics and human rights, but the nation is still ranked 144 out of 177 countries in Transparency International's corruption index.

The Ukrainians who have taken to the streets say they want to see a better governed, less corrupt and politically liberal country, more closely aligned with its western neighbors.

Ukraine's economy has been slow to follow its western neighbors that were also under Soviet control -- Poland, for example, where the economy has grown exponentially.

Many Ukrainians hope that an EU deal would offer the chance of economic recovery.

How does this affect the United States?

The United States has been among the Western governments calling for an end to the violence and a solution through political dialogue -- but some say it has not been the most vocal.

Washington has released several statements voicing concern about the crisis, and top officials have spoken on the phone to Kiev.

U.S. Vice President Joe Biden called Yanukovych on Monday night to reiterate American support for "a peaceful, political solution to the crisis," the White House said.

In December, U.S. Sen. John McCain, who has been critical of Ukrainian authorities' use of force against demonstrators, and Sen. Christopher Murphy traveled to Kiev and met with the protesters.

"The U.S. seems to be treading carefully to avoid getting crosswise with Russia at a moment when Moscow's support is critical for what the U.S. is trying to do on Syria and Iran," said Jeffrey Mankoff, deputy director and fellow with the Center for Strategic and International Studies' Russia and Eurasia Program.

"It's wise for the U.S. to avoid making Ukraine into a bellwether for relations with Russia, and for encouraging both sides in Kiev to seek a negotiated settlement, but some of the Europeans are already unhappy at what they see as a lack of U.S. leadership ion this issue."