- NEW: Residents say armed militants seized the police station in Kramatorsk, Ukraine
- Ukraine claims photographs show Russian troops in eastern Ukraine
- Russian Foreign Minister Sergey Lavrov says Geneva pact not being implemented
- Vice President Joe Biden delivers aid package in visit to Kiev
Slaviansk, Ukraine (CNN) -- Do a series of photos of gun-toting men wearing green uniforms prove Russian forces are operating in eastern Ukraine?
Ukrainian officials point to the pictures in a dossier obtained Monday by CNN, arguing that the images show Russian "sabotage-reconnaissance groups" acting in Ukrainian towns.
The images, Ukrainian officials say, prove organized Russian activity in the region.
CNN cannot independently confirm the photographs, some of which were first published in The New York Times.
The dossier shows what Ukrainian officials say are images of well-equipped gunmen in eastern Ukraine who look similar to photographs of Russian forces taken in Crimea, Russia and during Russia's 2008 invasion of Georgia.
Last week, Ukrainian security officials told CNN they had arrested a Russian military officer and a woman Ukrainian officials said is a Russian intelligence agent.
Moscow has disavowed involvement in the takeover of government buildings in eastern Ukraine or other acts by often-masked pro-Russian gunmen.
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Rubin: 'Little chance' of calm in Ukraine But the photos, accepted as genuine by the Obama administration, appeared to lend credence to allegations by Ukrainian officials that Russian forces have been dispatched in eastern Ukraine to provoke a military confrontation.
If genuine, the photos also back up Western leaders who have claimed Russia's involvement. Last week, NATO commander Gen. Philip Breedlove wrote on the alliance's blog that what pro-Russian groups have described as an organic uprising is in reality a "well-planned and organized" military operation orchestrated by Moscow.
"There has been broad unity in the international community about the connection between Russia and some of the armed militants in eastern Ukraine, and the photos presented by the Ukrainians last week only further confirm this, which is why U.S. officials have continued to make that case," State Department spokesman Jen Psaki told CNN on Monday.
The question of whether Russia is involved in the unrest roiling eastern Ukraine is crucial as European observers try to enforce an agreement reached last week to lower tensions in the region by organizing the withdrawal of forces from government buildings and other facilities.
Officials who brokered the deal in Geneva said they hoped it would ease tensions. But there were some signs Monday that tensions are mounting.
Residents told CNN that armed militants seized the police station in Kramatorsk, Ukraine, late Monday. The police station had been stormed on April 12 before being handed back to local officials two days later.
Amateur video from the scene shows masked, armed men escorting the local police chief to a car after seizing the building.
The video, in addition to the photos released by Ukrainian officials, seemed to show that at least some forces in Ukraine show no sign of backing down.
Ukraine provided the photos to those observers from the Organization for Security and Cooperation in Europe, according to the briefing dossier obtained by CNN's Elise Labott.
One image shows a gunman with a long beard during an assault on a police station in Kramatorsk who appears similar to a Russian special forces member photographed during the Russian invasion of Georgia.
Another shows gunmen photographed occupying administrative buildings in Slaviansk who appear similar to men pictured in what Ukrainian officials described as a "family photo" of a Russian sabotage and reconnaissance unit.
Natacha Rajakovic, deputy spokeswoman for the Organization for Security and Cooperation in Europe, declined to comment on the images and referred questions to Ukrainian authorities.
Ukrainians maintain that Russian involvement in the east is widespread.
CNN has heard Russian accents among the "men in green," as they are known, well armed and uniformed groups who have appeared in towns like Slaviansk and Kramatorsk. One told CNN he had come up from Crimea. But CNN has not seen any evidence that these men are operating under orders from the Kremlin.
Russia's Foreign Minister scoffed at the accusations, saying that Kiev and its patrons, the United States and the European Union, are trying to blame his country for everything.
Slaviansk's self-declared mayor, a former military man himself, says the explanation is simple: He put out an appeal to his old comrades.
"When I called on my friends, practically all of whom are ex military, they came to our rescue, not only from Russia but also from Belarus, Kazakhstan and Moldova," he said.
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SLOVYANSK, UKRAINE: "Welcome to Balaclavistan! This happy chap wouldn't say if he's Crimean, Russian or Ukrainian." - CNN's Christian Streib. Follow Christian on Instagram at http://ift.tt/1oUPDqV. 
EASTERN UKRAINE: "Ukrainian Police checkpoint north of Donetsk. A rare sight these days in Eastern Ukraine." - CNN's Christian Streib, April 15. Follow Christian on Instagram at http://ift.tt/1oUPDqV. 
NEAR KIEV, UKRAINE: "Fresh recruits to Ukraine's National Guard Reserves (March 20). All of them are former anti-government militiamen from Kyiv's Maydan. They've all signed up within the last week as part of a mass recruitment program announced by the interim Ukrainian government." - CNN's Ivan Watson. WATCH THE INSTAGRAM VIDEO from Ivan of a curious "hand grenade" simulation exercise performed by new Ukrainian National Guard reserve recruits. Follow Ivan on Instagram at http://ift.tt/I46jhH. 
SIMFEROPOL, CRIMEA: "Early morning departure (March 19) at Simferopol airport where the Russian flag is already firmly in place on the tarmac." - CNN's Dominique Van Heerden. Follow Dominique on Instagram at http://ift.tt/1c5vmhP. 
SIMFEROPOL, UKRAINE: "Celebrations already well underway here in Lenin Square in Simferopol (March 16)." - CNN's Dominique Van Heerden. Follow Dominique on Instagram at http://ift.tt/1c5vmhP. 
KIEV, UKRAINE: "The mood was grim in Kyiv's Maydan (March 16), as a mustachioed Ukrainian Cossack beat a kettle drum during the separatist referendum in Crimea." - CNN's Ivan Watson. WATCH THE INSTAGRAM VIDEO Follow Ivan on Instagram at http://ift.tt/I46jhH. 
SIMFEROPOL, UKRAINE: "Voting has started in Crimea (March 16). Steady stream of voters at this polling station in the center of Simferopol." - CNN's Dominique Van Heerden. Follow Dominique on Instagram at http://ift.tt/1c5vmhP. 
DONETSK, UKRAINE: Demonstrators wave revolutionary flags at a major pro-Russia rally in Lenin Square in central Donetsk (March 15). Some are calling for independence from Ukraine. Others are calling for union with Russia. Photo by CNN's Kellie Morgan. 
SIMFEROPOL, UKRAINE: "Pro-Soviet flags being made and handed out in Simferopol on March 14." - CNN's Michael Holmes. Follow Michael on Instagram at http://ift.tt/OdqKLU. 
SIMFEROPOL, UKRAINE: "You really don't have to wander very far in Simferopol (March 14) to find posters like this one around parliament and Lenin Square." - CNN's Dominique Van Heerden. Follow Dominique on Instagram at http://ift.tt/1c5vmhP 
KIEV, UKRAINE: "Protesters outside parliament in Kiev on March 12 call for the release of 34 political prisoners arrested during demonstrations." - CNN's Dominique Van Heereden. Follow Dominique on Instagram at http://ift.tt/1c5vmhP 
DONETSK, UKRAINE: "Dominating the main square named after him: Vladimir Ilyich Ulyanov, also known as Lenin" - CNN's Christian Streib. Follow Christian on Instagram at http://ift.tt/1oUPDqV. 
KIEV, UKRAINE: CNN cameraman Scott McWhinnie films volunteers peeling vegetables, preparing meals for protesters still living in tents in Maidan, also known as Independence Square, on March 9. Photo by CNN's Michael Holmes. Follow Michael on Instagram at http://ift.tt/OdqKLU. 
SEVASTOPOL, UKRAINE: The Ukranian Navy vessel Slavutych remains blocked by Russian Navy boats inside the Port of Sevastopol on March 10, photographed by CNN's Christian Streib. Follow Christian on Instagram at http://ift.tt/1oUPDqV. 
SEVASTOPOL, UKRAINE: "CNN's Matthew Chance and team talk to the first officer of the Ukrainian Intelligence Navy ship Slavutych inside the Port of Sevastopol on March 10." - CNN's Christian Streib. Follow Christian on Instagram at http://ift.tt/1oUPDqV. 
KIEV, UKRAINE: People stream through Independence Square, laying flowers, and lighting candles. like the ones pictured here on March 9. Photo by CNN's Dominique Van Heerden. Follow Dominique on Instagram at http://ift.tt/1c5vmhP 
KIEV, UKRAINE: An aerial photo of Independence Square, or Maidan, in Kiev on March 8. Many remain camped out in Independence Square, while others stream through the area to pay tribute to those who were killed. Photo by CNN's Tony Umrani. 
KIEV, UKRAINE: A giant EU flag is hung outside the foreign ministry building in Kiev on March 7. Photo by CNN's Dominique Van Heerden. Follow Dominique on Instagram at http://ift.tt/1c5vmhP. 
SOUTHERN UKRAINE: Gunmen block monitors from the Organization for Security and Co-operation in Europe (OSCE) who are trying unsuccessfully to negotiate their way into Crimea past pro-Russian border patrols on March 7. Photo by CNN's Christian Streib. Follow Christian on Instagram at http://ift.tt/1oUPDqV 
KIEV, UKRAINE: CNN's Anderson Cooper reports from Kiev's Independence Square on March 6. Photo by CNN's Khalil Abdallah. 
KIEV, UKRAINE: Portraits of people killed during clashes with riot police are left with candles and flowers at Kiev's Independence Square on March 6. Photo by CNN's Michael Holmes. Follow Michael on Instagram at http://ift.tt/OdqKLU. 
SEVASTOPOL, UKRAINE: Cameraman Chris Jackson captures the Russian Black Sea fleet in Sevastopol on March 5. Photo by CNN's Ben Wedeman. Follow Ben on Instagram at http://ift.tt/OdqL2s. 
KIEV, UKRAINE: "Cutting wood to keep volunteers warm as they continue to guard Independence Square in Kiev." - CNN's Khalil Abdallah on March 5. Follow Khalil on Instagram at http://ift.tt/1oUPDHp. 
WASHINGTON, DC: Ukrainian demonstrators rally on March 5 outside the White House against the Russian incursion into Crimea. Photo by CNN's Burke Buckhorn. Follow Burke on Instagram at http://ift.tt/1oUPFz0 
SEVASTOPOL, UKRAINE: "A massive statue on a hill overlooking Sevastopol, dedicated to the unity of the Soviety army and navy during World War II. After a brutal 250-day siege by German forces, Sevastopol fell in 1942. The past weighs heavily here, with an intense awareness of history, of identity, of place." - CNN's Ben Wedeman. Follow Ben on Instagram at http://ift.tt/OdqL2s. 
SEVASTOPOL, UKRAINE: "A weary Ukrainian soldier after a five-day standoff at the Belbak air base outside Sevastopol, Crimea, on March 5." - CNN's Ben Wedeman. Follow Ben on Instagram at http://ift.tt/OdqL2s. 
KIEV, UKRAINE: The Shrine of the Fallen on Institutska Street honors the "Heroes" killed in clashes with police. Photo on March 4 by CNN's Dominique Van Heerden. Follow Dominique on Instagram at http://ift.tt/1c5vmhP. 
KIEV, UKRAINE: CNN Cameraman Christian Streib sets up for live shots by the barricades on the road to Independence Square on March 4. Photo by CNN's Jon Steward. 
KIEV, UKRAINE: "27-year old Bogdan sits on top of his Russian-made soup kitchen in Indepence -- or Maidan -- Square on March 2. He's been sitting there for the last three months serving delicious Ukrainian grechaniy soup. It's made of buckwheat, lentil, coriander and beef. Amazing taste." - CNN's Christian Streib. Follow Christian on Instagram at http://ift.tt/1oUPDqV. 
PEREVALNOYE BASE, UKRAINE: "Outside Ukrainian base in Crimea (March 2), tight-lipped but obviously Russian marines deploy around perimeter as Ukrainian soldiers inside vow not to surrender." - CNN's Ben Wedeman. Follow Ben on Instagram at http://ift.tt/OdqL2s. 
KIEV, UKAINE: "Perhaps the best solution to end the crisis in Ukraine." - CNN's Christian Streib on March 2. Follow Ben on Instagram at http://ift.tt/OdqL2s. 
KIEV, UKRAINE: "APC in central Kiev (March 1). It appeared the morning after Russian forces moved into the Crimea." -- CNN's Ian Lee. Follow Ian on Instagram at http://ift.tt/OdqLzi. 
KIEV, UKRAINE: A young girl pays tribute to anti-government protesters killed in the clashes with riot police by placing a flower on a makeshift memorial leading to the barricades in central Kiev on February 24. Photo by CNN's Todd Baxter. 
KIEV, UKRAINE: A woman mourns at a makeshift memorial (February 23) in homage to anti-government protesters killed in clashes with riot police in Kiev's Independence Square. Photo by CNN's Todd Baxter. 
KIEV, UKRAINE: Bullet holes in a power pole at a spot where a protester was killed during clashes with riot police, near Independence Square. Photo by CNN's Todd Baxter on February 23. 
KIEV, UKRAINE: Ukrainians are reflected in a puddle as they gather to mourn the dead in Maidan Square on February 23, after protesters succeeded in forcing President Viktor Yanukovich out of office. Photo by CNN's Christian Streib. Follow Christian on Instagram at http://ift.tt/1oUPDqV. 
KIEV, UKRAINE: "Anti-government demonstrator in makeshift riot gear (February 22), a member of several protection units set up by the organizers of the occupation of Maidan Square." - CNN's Christian Streib. Follow Christian on Instagram at http://ift.tt/1oUPDqV. 
KIEV, UKRAINE: Defected policemen and anti-government protesters at barricades together in central Kiev on February 21. Photo by CNN's Fred Pleitgen. Follow Fred on Instagram at http://ift.tt/OdqNHH. 
KIEV, UKRAINE: Anti-government protesters clash with riot police in central Kiev on February 20. Photo by CNN's Todd Baxter. 
KIEV, UKRAINE: Riot police face anti-government protesters during clashes in central Kiev on February 20. Photo by CNN's Todd Baxter. 
KIEV, UKRAINE: After the deaths of 25 people during clashes a day earlier, Ukrainian protesters prepare to stand and fight again on February 19. Photo taken by CNN's Andrew Carey on February 19. 
KIEV, UKRAINE: "This 17 year old protestor was taken by police as he was watching the clashes (January 23) while taking iPhone photos. He was stripped naked, beaten, stabbed in the thigh and his arm was broken. He faces eight to fifteen years in jail for taking part in a mass demonstration. The government has labeled those taking part in the violence as 'terrorists'." - CNN's Diana Magnay. 
KIEV, UKRAINE: Pro-Europe protesters pour into Independence square on December 14. Opposition supporters have been camping since Nov. 21 in Independence Square - in protest against President Yanukovich's last minute refusal to sign an agreement bringing Ukraine closer to the European Union, in favor of Russia. Photo by CNN's Diana Magnay. 
KIEV, UKRAINE: Ukrainian riot police storm barricades set up by pro-European Union protesters in Independence Square on December 11. Ukrainian security forces stormed the square, which protesters have occupied for three weeks. The demonstrators defiantly refused to leave and resisted the police in a tense standoff. Photo by CNN's Diana Magnay. Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Ukraine, captured by CNN Teams on assignment.
Crisis in Ukraine, captured by CNN Teams on assignment.
Crisis in Ukraine, captured by CNN Teams on assignment.
Crisis in Ukraine, captured by CNN Teams on assignment.
Crisis in Ukraine, captured by CNN Teams on assignment.
Crisis in Ukraine, captured by CNN Teams on assignment.
Crisis in Ukraine, captured by CNN Teams on assignment.
Crisis in Ukraine, captured by CNN Teams on assignment.
Ukraine Crisis captured by CNN Teams
Crisis in Ukraine, captured by CNN Teams on assignment.
Ukraine crisis captured by CNN Teams
Ukraine Crisis captured by CNN Teams
Ukraine Crisis captured by CNN Teams
Ukraine crisis captured by CNN Teams
Ukraine crisis captured by CNN Teams
Ukraine crisis captured by CNN Teams
Ukraine crisis captured by CNN Teams
Ukraine crisis captured by CNN Teams
Ukraine crisis captured by CNN Teams
Ukraine crisis captured by CNN Teams
Ukraine Crisis captured by CNN Teams
Ukraine crisis captured by CNN Teams
Ukraine crisis captured by CNN Teams
Crisis in Ukraine, captured by CNN Teams on assignment.
Crisis in Ukraine, captured by CNN Teams on assignment.
Ukraine crisis captured by CNN Teams
Ukraine crisis captured by CNN Teams
Ukraine crisis captured by CNN Teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Ukraine crisis captured by CNN Teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Crisis in Crimea and Ukraine, captured by CNN teams
Photos: Crisis in Crimea and Ukraine 
An armed pro-Russian man stands on a street in Sloviansk, Ukraine, on Monday, April 21. Ukraine has seen a sharp rise in tensions since a new pro-European government took charge of the country in February. Moscow branded the new government illegitimate and annexed Ukraine's Crimea region last month, citing threats to Crimea's Russian-speaking majority. And in eastern Ukraine, pro-Russian separatists have seized government and police buildings in numerous towns and cities. 
U.S. Vice President Joe Biden arrives at Boryspil International Airport near Kiev on April 21. 
Demonstrators attend a pro-Russian rally outside the secret service building in Lugansk, Ukraine, on April 21. 
Cars are burned out after an attack at a roadblock in Slaviansk on Sunday, April 20. 
A resident inspects burnt-out cars at the roadblock on April 20. 
A pro-Russian militant is seen at the roadblock near Slaviansk on April 20. 
Armed pro-Russian militants stand guard at the roadblock near Slaviansk on April 20. 
A masked man stands guard outside a regional administration building seized by pro-Russian separatists in Slaviansk, Ukraine, on Friday, April 18. 
People walk around barricades April 18 set up at the regional administration building seized earlier in Donetsk, 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 admit for the first time that Russians were active in Crimea before the peninsula voted to join the country. 
Ukrainian riot police officers stand guard during a pro-Ukrainian demonstration in Donetsk on April 17. 
Masked pro-Russian protesters stand guard in front of the city hall in Mariupol, Ukraine, on April 17. 
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. 
A masked gunman stands guard near tanks in Slaviansk, Ukraine, on Wednesday, April 16. 
A Ukrainian helicopter flies over a column of Ukrainian Army combat vehicles on the way to Kramatorsk, a city in eastern Ukraine, on April 16. 
A masked pro-Russian gunman guards combat vehicles parked in downtown Slaviansk on April 16. 
A man talks with Ukrainian soldiers as they are blocked by people on their way to Kramatorsk. 
Ukrainian soldiers sit atop combat vehicles on their way to Kramatorsk. 
Ukrainian Gen. Vasily Krutov is surrounded by protesters after addressing the crowd outside an airfield in Kramatorsk on Tuesday, April 15. 
Pro-Russian activists guard a barricade April 15 outside the regional police building that they seized in Slaviansk. 
Ukrainian troops receive munitions at a field on the outskirts of Izium, Ukraine, on April 15. 
Armed pro-Russian activists stand guard on top of a Ukrainian regional administration building in Slaviansk on Monday, April 14. 
A pro-Russian activist carries a shield during the mass storming of a police station in Horlivka, Ukraine, on April 14. 
Russian supporters attend a rally in front of the security service building occupied by pro-Russian activists in Luhansk, Ukraine, on April 14. 
A man places a Russian flag over a police station after storming the building in Horlivka on April 14. 
Men besiege the police station in Horlivka. 
The Horlivka police station burns on April 14. 
A Ukrainian police officer receives medical care after being attacked at the police station in Horlivka on April 14. 
Pro-Russian supporters beat a pro-Ukrainian activist during a rally in Kharkiv, Ukraine, on Sunday, April 13. 
Pro-Russian activists escort a man outside the secret service building in Luhansk on April 13. 
Pro-Russian protesters guard a barricade in Slaviansk on April 13 outside a regional police building seized by armed separatists the day before. 
Armed pro-Russian activists carrying riot shields occupy a police station in Slaviansk on April 12. 
A group of pro-Russian activists warm themselves by a fire Friday, April 11, in front of a Ukrainian Security Service office in Luhansk. 
Ukrainian Prime Minister Arseniy Yatsenyuk speaks April 11 during his meeting with regional leaders in Donetsk, Ukraine. Yatsenyuk flew into Donetsk, where pro-Russian separatists occupied the regional administration building and called for a referendum. 
Pro-Russian young men look over the fence of a military recruitment office in Donetsk on Thursday, April 10. 
Armed pro-Russian protesters occupy the Security Service building in Luhansk on April 10. 
Members of the self-proclaimed government the "Donetsk Republic" vote April 10 during a meeting at the seized regional administration building in Donetsk. 
Ukrainian lawmakers from different parties scuffle during a Parliament session in Kiev, Ukraine, on Tuesday, April 8. 
Workers clean up on April 8 after pro-Russian separatists and police clashed overnight in Kharkiv. 
Pro-Russian protesters burn tires near a regional administration building in Kharkiv after police cleared the building on Monday, April 7. 
A masked man stands on top of a barricade at the regional administration building in Donetsk on April 7. 
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. 
Pro-Russian protesters clash with police as they try to occupy a regional administration building in Donetsk on April 6. 
Pro-Russian activists hold a rally in front of a Ukrainian Security Service office in Luhansk on April 6. 
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. 
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. 
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. 
Soviet military veterans take part in a flower-laying ceremony at the Soviet-era World War II memorial in Sevastopol on Thursday, April 3. 
Ukrainian soldiers conduct a training session on the Desna military shooting range northeast of Kiev on Wednesday, April 2. 
Russian soldiers prepare for diving training in front of a Tarantul-III class missile boat Tuesday, April 1, in Sevastopol. 
People pass by barricades near the Dnipro Hotel in Kiev on April 1. 
People walk past a train loaded with Russian tanks Monday, March 31, in the Gvardeyskoe railway station near Simferopol, Crimea. 
A Russian solder sits in a tank at the Ostryakovo railway station, not far from Simferopol on March 31. 
Russian Prime Minister Dmitry Medvedev speaks about the economic development of Crimea during a meeting March 31 in Simferopol. 
Members of the Ukrainian National Guard take part in military exercises on a shooting range near Kiev on March 31. 
A woman cries Sunday, March 30, during a gathering to honor those who were killed during protests in Kiev's Independence Square. 
A woman and child walk past a line of police officers during a rally in Kharkiv on March 30. 
Ukrainian soldiers take part in a training exercise at a military base in Donetsk on Saturday, March 29. 
Demonstrators protest Friday, March 28, in Kiev, displaying police vehicles they seized during earlier clashes with authorities. 
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. 
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. 
Ukrainian marines wave as they leave a base in Feodosia, Crimea, on Tuesday, March 25. 
Russian sailors stand on the deck of the corvette ship Suzdalets in the bay of Sevastopol on March 25. 
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. 
Soldiers in unmarked uniforms sit atop an armored personnel carrier at the gate of the Belbek air base on March 22. 
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. 
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. 
A Ukrainian serviceman leaves a Ukrainian military unit that Russian soldiers took control of in Perevalne on March 21. 
Ukrainian border guards run during training at a military camp in Alekseyevka, Ukraine, on March 21. 
Russian soldiers patrol the area surrounding a Ukrainian military unit in Perevalne on Thursday, March 20. 
Pro-Russian protesters remove the gate to the Ukrainian navy headquarters as Russian troops stand guard in Sevastopol on Wednesday, March 19. 
Pro-Russian forces walk inside the Ukrainian navy headquarters in Sevastopol on March 19. 
A member of pro-Russian forces takes down a Ukrainian flag at the Ukrainian navy headquarters in Sevastopol on March 19. 
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. 
A Russian flag waves as workers install a new sign on a parliament building in Simferopol, Crimea's capital, on March 19. 
Russian military personnel surround a Ukrainian military base in Perevalne on March 19. 
Nameplates on the front of the Crimean parliament building get removed Tuesday, March 18, in Simferopol. 
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. 
Demonstrators hold a Crimean flag at Lenin Square in Simferopol on March 18. 
Ukrainian soldiers stand guard at a checkpoint near Strilkove, Ukraine, close to Crimea on Monday, March 17. 
Former boxer and Ukrainian politician Vitali Klitschko addresses reporters in Kiev on March 17. 
Ukrainian troops stand guard in front of the Ukrainian Parliament building in Kiev on March 17. 
A Ukrainian man applies for the National Guard at a mobile recruitment center in Kiev on March 17. 
Civilians walk past riot police in Simferopol on March 17. 
A Ukrainian soldier stands on top of an armored vehicle at a military camp near the village of Michurino, Ukraine, on March 17. 
Policemen stand guard outside the regional state administration building in Donetsk during a rally by pro-Russia activists March 17. 
Armed soldiers stand guard outside a Ukrainian military base in Perevalne on March 17. 
A man holds a Crimean flag as he stands in front of the Crimean parliament building in Simferopol on March 17. 
Crimeans holding Russian flags celebrate in front of the parliament building in Simferopol on Sunday, March 16. 
A Ukrainian police officer tries to shield himself from a road block thrown by pro-Russia supporters in Kharkiv on March 16. 
Pro-Russia demonstrators storm the prosecutor general's office during a rally in Donetsk on March 16. 
A woman leaves a voting booth in Sevastopol on March 16. See the crisis in Ukraine before Crimea voted Photos: Crisis in Ukraine But on Monday, he insisted there are no active duty Russian soldiers in his town.
Diplomatic efforts
The government of acting Ukrainian President Oleksandr Turchynov has talked tough but done little to curb pro-Russian activities in the east, possibly afraid that a crackdown could send Russian forces across the border. The occupation of buildings continued in about a dozen towns and cities across eastern Ukraine.
International monitors from the Organization for Security and Cooperation in Europe met Monday with pro-Russian leaders in Slaviansk, but no breakthroughs were reported.
The monitors were called for in the agreement among Russia, the United States and the European Union last week that was meant to reduce tensions in the region, which while part of Ukraine has long looked toward Russia for cultural and economic ties.
In three towns, pro-Russian protesters and militants have made it clear to CNN they have no intention of moving until the "illegal" government in Kiev also moves out of official buildings.
Russian Foreign Minister Sergey Lavrov echoed those sentiments Monday, saying that Ukrainian officials were not implementing the agreement negotiated in Geneva, Switzerland.
"On the contrary, not a single step has been taken by those who have seized power in Kiev to eliminate the reasons of this deep crisis inside Ukraine," he said.
Russia has said before that it holds no sway over pro-Russian protesters and militants.
Geoffrey Pyatt, the U.S. ambassador to Ukraine, told CNN's Candy Crowley on Sunday that he has seen progress. He had just met with Ukrainian Foreign Minister Andriy Deshchytsia and the ambassador who heads the OSCE's special monitoring mission, along with his European Union and Russian counterparts.
"I think we all reaffirmed today in this setting our collective commitment to trying to make the Geneva framework a success," he said on CNN's "State of the Union." "There are obviously some real challenges at this point," including the violence in Slaviansk.
"But we also believe that there has been some progress. I'm seeing reports this morning that at least one of these (occupied) government buildings now has a Ukrainian flag flying over it," he said. "And the OSCE has monitors on the ground who are reaching out, engaging with local political elites, seeing if there's a way to de-escalate the crisis."
There is "no military solution" to the crisis, Pyatt said. "It has to be solved through diplomacy."
Biden visits Kiev
Meanwhile, U.S. Vice President Joe Biden arrived Monday in Kiev to discuss the situation in eastern Ukraine and deliver a new aid package aimed at shoring up the Ukrainian government.
The bundle includes new economic and energy aid as well as governance assistance, a senior administration official told reporters in a background briefing Monday.
It's likely to sit well with Ukrainian leaders struggling to keep their country going amid widespread financial problems and a growing showdown with Russia over that country's annexation of Crimea and troubles in Ukraine's pro-Russian east.
On the streets of Kiev, ordinary citizens said they know there's only so much the United States can do. Some said they'd like to see the U.S. send troops.
"Our army is very bad. Maybe the U.S. can give us some military help," one Ukrainian said.
But others say that's too much, even with pro-Russian forces occupying government buildings in the east and thousands of Russian troops massed along the Ukrainian border.
"I think we want consultations, but no American troops," another Ukrainian citizen told CNN.
U.S. officials have ruled out the possibility of deploying U.S. forces to Ukraine.
But some U.S. lawmakers have argued that the United States should send weapons.
That wouldn't help the situation and might make it worse, U.S. Deputy National Security Adviser Ben Rhodes told CNN's "The Lead with Jake Tapper" on Monday.
It won't take sending weapons, Rhodes said, to send a message to Russia.
"We've signaled how we can escalate our sanctions," he said. "In the long run, if Russia runs this play, they're going to lose a lot."
Speaking to CNN from Kiev on Monday, Rep. Ed Royce said the United States needs to do more to reduce Ukraine's reliance on natural gas and oil from Russia by exporting fuel there from the United States.
"What has put Putin in the driver's seat over here is the fact that he controls oil and gas. He's got a monopoly on it," the California Republican said. "And that would be something we could upset."
Defense Secretary Chuck Hagel said last week that the United States, however, will continue its beefed-up presence in Poland because of the crisis. Among fellow members of NATO, Poland has expressed particular concern about Russian plans in Ukraine.
The Defense Department is also sending some nonlethal aid to Ukrainian security forces, including medical supplies, helmets, shelters and water purification equipment.
Read: Pro-Russian separatists in Ukraine ignore new Geneva pact aimed at easing tensions
Read: Opinion: Why Geneva accord on Ukraine is a tactical victory for Russia
Read: Opinion: How Ukraine crisis could pull U.S. to war
CNN's Frederik Pleitgen, Tim Lister, Elena Sandyrev, Phil Black, Alla Eshchenko, Elaine Ly and Lena Kashkarova contributed to this report.
