Pro-Russian rebels fire artillery Tuesday, October 14, at Donetsk Sergey Prokofiev International Airport, which is on the outskirts of Donetsk, Ukraine. Fighting between Ukrainian troops and pro-Russian rebels in the country has left more than 3,000 people dead since mid-April, according to the United Nations. Dmitry Lovetsky/ap
Smoke rises behind the train station in Donetsk, Ukraine, during an artillery battle between pro-Russian rebels and Ukrainian government forces on Sunday, October 12. Dmitry Lovetsky/AP
Ukrainian President Petro Poroshenko, center, inspects Ukrainian army positions close to Donetsk on Friday, October 10. Mykhailo Palinchak/pool/ap
The main terminal of Donetsk Sergey Prokofiev International Airport is hit by shelling during fighting between pro-Russian rebels and Ukrainian forces on Wednesday, October 8. Dmitry Lovetsky/AP
Pro-Russian rebels fire mortars toward Ukrainian positions near to the Donetsk airport on October 8. Dmitry Lovetsky/AP
A pro-Russian rebel walks past a burning house after shelling in the town of Donetsk, Ukraine, on Sunday, October 5. Dmitry Lovetsky
An Ukrainian sniper aims his weapon at a checkpoint near Popasna, Ukraine, on Thursday, October 2. Anatolii Boiko/AFP/Getty Images
Smoke rises from the area near the Donetsk airport after heavy shelling on October 2. John MacDougall/AFP/Getty Images
An injured man is transported at a hospital after shelling in Donetsk on Wednesday, October 1. JOHN MACDOUGALL/AFP/Getty Images
A woman injured at a bus station cries at a Donetsk hospital on October 1. JOHN MACDOUGALL/AFP/Getty Images
A pro-Russian rebel guards a damaged school in Donetsk on October 1. Darko Vojinovic/AP
Ukrainian servicemen patrol in the Donetsk region on Friday, September 26. ANATOLII BOIKO/AFP/Getty Images
A pro-Russian rebel guards a destroyed bridge in Nyzhnya Krynka, Ukraine, on Tuesday, September 23. Darko Vojinovic/AP
Residents clean up debris at a building damaged by rockets in Debaltseve, Ukraine, on Monday, September 22. ANATOLII STEPANOV/AFP/Getty Images
A firefighter checks out a damaged office building after shelling in Donetsk on Sunday, September 21. Darko Vojinovic/AP
A Ukrainian soldier guards pro-Russian rebels during a prisoner exchange near Donetsk on September 21. Darko Vojinovic/AP
Members of the Ukrainian military, held as prisoners of war, sit in a bus waiting to be exchanged near Donetsk on Saturday, September 20. Darko Vojinovic/AP
Smoke rises after an explosion at a weapons factory controlled by pro-Russian rebels near Donetsk on September 20. The cause of the explosion was not immediately known. PHILIPPE DESMAZES/AFP/Getty Images
A Ukrainian helicopter patrols an area near Donetsk on September 20. ANATOLII STEPANOV/AFP/Getty Images
A firefighter walks past the rubble of a building destroyed by shelling in Donetsk on Wednesday, September 17. PHILIPPE DESMAZES/AFP/Getty Images
A protester holds a smoke bomb during a demonstration outside the Presidential Palace in Kiev, Ukraine, on September 17. Activists protested the adoption of legislation giving greater autonomy to rebel-held parts of eastern Ukraine's Donetsk and Luhansk regions. GENYA SAVILOV/AFP/Getty Images
A man covers the body of his mother, who was killed on a bus during a battle in Donetsk on Tuesday, September 16. Darko Vojinovic/AP
People walk through a market Monday, September 15, in the Kievsky district of Donetsk. PHILIPPE DESMAZES/AFP/Getty Images
Smoke rises around the Donetsk International Airport on Saturday, September 13, as shelling continues between pro-Russian rebels and the Ukrainian army. PHILIPPE DESMAZES/AFP/Getty Images
A Ukrainian soldier stands guard as residents rally in support of a united Ukraine in the southern Ukrainian city of Mariupol on September 13. Alexander KHUDOTEPLY/AFP/Getty Images
Russian trucks, flying Russian flags and carrying humanitarian aid for eastern Ukraine, line up at a border checkpoint in Donetsk on September 13. AP
Workers unload supplies from Russia in Luhansk, Ukraine, on September 13. More than 200 Russian trucks entered Ukraine with supplies for the city, which has been cut off from electricity and water for weeks. /Darko Vojinovic/AP
Ukrainian soldiers ride on an armored vehicle near Kramatorsk, Ukraine, on September 13. ANATOLII STEPANOV/AFP/Getty Images
People look at a large crater from a reported missile strike that hit a bus station Friday, September 12, in Makiivka, Ukraine. PHILIPPE DESMAZES/AFP/Getty Images
Workers clear rubble Thursday, September 11, after the bombing of a mine in Donetsk. Sergei Grits/AP
A column of Ukrainian forces is seen in Volnovakha, Ukraine, on September 11. ANATOLII STEPANOV/AFP/Getty Images
An elderly woman sits next to a Ukrainian soldier standing guard in Volnovakha on September 11. ANATOLII STEPANOV/AFP/Getty Images
Armed pro-Russian rebels walk September 11 in front of the destroyed Luhansk International Airport. The rebels took control of the airport on September 1 after heavy fighting with the Ukrainian army. PHILIPPE DESMAZES/AFP/Getty Images
Residents of Lutuhyne, Ukraine, push containers in a wheelbarrow September 11 as they walk between destroyed armored vehicles left behind by the Ukrainian army. PHILIPPE DESMAZES/AFP/Getty Images
Ukrainian troops protect themselves from a nearby shooting in Debaltseve on Tuesday, September 9. ANATOLII STEPANOV/AFP/Getty Images
Young residents of Berdyansk, Ukraine, dig trenches September 9 to help Ukrainian forces protect the city from possible rebel attacks. ALEKSEY CHERNYSHEV/AFP/Getty Images
Ukrainian President Petro Poroshenko, left, inspects military personnel during a visit to Mariupol on Monday, September 8. Mikhail Palinchak/ap
A pro-Russian rebel stands next to a truck with a heavy machine gun attached to it Sunday, September 7, in Donetsk. Sergei Grits/AP
Homes smolder after being hit by shelling in Donetsk on September 7. Sergei Grits/AP
A woman stands next to a road sign September 7 after an overnight bombing attack at an Ukrainian army checkpoint on the outskirts of Mariupol. PHILIPPE DESMAZES/AFP/Getty Images
Ukrainian troops stand on a deserted road as they patrol the border area of the Donetsk and Luhansk regions Friday, September 5, near Debaltseve. ANATOLII STEPANOV/AFP/Getty Images
A man repairs damage to a building caused by shelling in Donetsk on September 5. FRANCISCO LEONG/AFP/Getty Images
Smoke rises on the outskirts of Mariupol after pro-Russian rebels fired heavy artillery on September 5. PHILIPPE DESMAZES/AFP/Getty Images
Ukrainian soldiers ride a tank on a road close to where pro-Russian rebels fired heavy artillery outside Mariupol on September 5. PHILIPPE DESMAZES/AFP/Getty Images
A wounded Ukrainian soldier is helped by a medical team on the outskirts of Mariupol on September 5. PHILIPPE DESMAZES/AFP/Getty Images
A pro-Russian rebel holds a destroyed weapon in the village of Novokaterynivka, Ukraine, on Thursday, September 4. ANATOLII BOIKO/AFP/Getty Images
Unmarked military vehicles burn on a country road in Berezove, Ukraine, on September 4 after a clash between Ukrainian troops and pro-Russian rebels. For months, Ukrainian government forces have been fighting the rebels near Ukraine's eastern border with Russia. Sergei Grits/AP
People wait by their cars near Berezove on September 4 as rockets hit the road ahead. Sergei Grits/AP
A pro-Russian rebel holds a dog, which has a hand grenade attached to its leash, in Donetsk on Wednesday, September 3. Mstyslav Chernov/ap
Pro-Russian rebels fire at Ukrainian army positions in Donetsk on September 3. Mstyslav Chernov/AP
A Ukrainian military vehicle patrols in the Donetsk region on September 3. ANATOLII STEPANOV/AFP/Getty Images
Pro-Russian rebels hold a man near a column of destroyed Ukrainian military vehicles in Novokaterynivka on Tuesday, September 2. Sergei Grits/AP
A Ukrainian military truck passes by a serviceman resting in his military camp in Ukraine's Donetsk region on September 2. ROMAN PILIPEY/EPA/LANDOV
A destroyed Ukrainian military vehicle sits abandoned on the side of the road near Novokaterynivka on September 2. Sergei Grits/AP
Men clear rubble in Ilovaisk, Ukraine, on Sunday, August 31. Sergei Grits/AP
Ukrainian troops leave the rebel-held town of Starobesheve on Saturday, August 30. Sergei Grits/ap
A Ukrainian loyalist fighter from the Azov Battalion stands guard on a hill on the outskirts of Mariupol on August 30. FRANCISCO LEONG/AFP/Getty Images
A pro-Russian rebel listens to the news on a transistor radio in the town of Novoazovsk, Ukraine, on Friday, August 29. Sergei Grits/ap
Ukrainian soldiers stop on a roadside as they wait for the start of their march into Mariupol on Wednesday, August 27. Sergei Grits/AP
A man opens a box filled with rocket-propelled grenades left by the Ukrainian army in Starobesheve. FRANCISCO LEONG/AFP/Getty Images
A pro-Russian rebel walks through a local market damaged by shelling in Donetsk on Tuesday, August 26. Mstislav Chernov/AP
Ukrainian servicemen of the volunteer battalion Azov leave for Novoazovsk on August 26. ALEXANDER KHUDOTEPLY/afp/getty images
Pro-Russian rebels escort captured Ukrainian soldiers in a central square in Donetsk on Sunday, August 24. Sergei Grits/AP
People yell as Ukrainian prisoners are paraded through Donetsk in eastern Ukraine on August 24. Sergei Grits/AP
A pro-Russian rebel delivers a speech atop a damaged Ukrainian armored personnel carrier in Donetsk on August 24. Sergei Grits/AP
People look at damaged Ukrainian military equipment in Donetsk on August 24. Sergei Grits/AP
The first trucks of a Russian aid convoy roll on the main road to Luhansk in eastern Ukraine on Friday, August 22. The head of Ukraine's security service called the convoy a "direct invasion" under the guise of humanitarian aid since it entered the country without Red Cross monitors. Sergei Grits/AP
A pro-Russian rebel holds shrapnel from a rocket after shelling in Donetsk on August 22. DIMITAR DILKOFF/AFP/Getty Images
Residents sit in a makeshift bomb shelter during a shelling in Makiivka on Wednesday, August 20. DIMITAR DILKOFF/AFP/Getty Images
Dogs play together as a Russian convoy carrying aid supplies stops at a border control point with Ukraine on August 20. Pavel Golovkin/AP
Ukrainian forces take their position not far from Luhansk on August 20. ANATOLII STEPANOV/AFP/Getty Images
Clouds of smoke are on the horizon as Ukrainian forces and pro-Russian rebels clash in Yasynuvata, Ukraine, on Tuesday, August 19. ANATOLII STEPANOV/AFP/Getty Images
An Ukrainian helicopter flies near Kramatorsk on August 19. ANATOLII STEPANOV/AFP/Getty Images
Ukrainian soldiers load a missile during fighting with pro-Russian rebels Monday, August 18, near Luhansk. Petro Zadorozhnyy/AP
Boys play at a refugee camp, set up by the Russian Emergencies Ministry, near the Russian-Ukrainian border on August 18. Pavel Golovkin/AP
Ukrainian soldiers carry weapons at a checkpoint near Debaltseve on Saturday, August 16. ANATOLII STEPANOV/AFP/Getty Images
Pro-Russian rebels greet each other as they pass near Krasnodon, Ukraine, on August 16. Sergei Grits/AP
A fireman tries to extinguish a fire after shelling in Donetsk on August 16. DIMITAR DILKOFF/AFP/Getty Images
Ukrainian border guards patrol near Novoazovsk on Friday, August 15. Alexander KHUDOTEPLY/AFP/Getty Images
Trucks of a Russian humanitarian convoy are parked in a field outside the town of Kamensk-Shakhtinsky, in the Rostov region of Russia about 20 miles from the Ukraine border, on August 15. Ukrainian officials were preparing to inspect the convoy, which was bound for the conflict-torn east. DMITRY SEREBRYAKOV/AFP/Getty Images
A truck driver from the convoy jumps out of a trailer on August 15. The Ukrainian government had expressed fears that the convoy was a large-scale effort to smuggle supplies or troops to pro-Russian rebels. ANDREY KRONBERG/AFP/Getty Images
A tank belonging to pro-Russian rebels moves along a street in Donetsk on August 15. DIMITAR DILKOFF/AFP/Getty Images
A Ukrainian soldier walks past a line of self-propelled guns as a column of military vehicles prepares to head to the front line near Ilovaisk on Thursday, August 14. Evgeniy Maloletka/AP
A Ukrainian soldier prepares a mortar at a position near Ilovaisk on August 14. Evgeniy Maloletka/AP
A man inspects damage at his house after a shelling in Donetsk on August 14. Sergei Grits/AP
A convoy of trucks, which Moscow said was carrying relief goods for war-weary civilians, moves from Voronezh, Russia, toward Rostov-on-Don, Russia, on August 14. Pavel Golovkin/AP
Pro-Russian rebels on the outskirts of Donetsk stand at a checkpoint near a bullet-riddled bus on Wednesday, August 13. Sergei Grits/AP
A pro-Russian rebel inspects damage after shelling in Donetsk on Thursday, August 7. Sergei Grits/AP
Smoke billows from a Ukrainian fighter jet crash near the village of Zhdanivka, Ukraine, on August 7. DIMITAR DILKOFF/AFP/Getty Images
Residents of eastern Ukraine cry in a hospital basement being used as a bomb shelter August 7 in Donetsk. Sergei Grits/AP
Ordnance from a Ukrainian rocket launcher shoots toward a pro-Russian militant position in the Donetsk region on August 7. ANATOLII STEPANOV/AFP/Getty Images
Relatives of Ukrainian military member Kyril Andrienko, who died in combat in eastern Ukraine, gather during his funeral in Lviv, Ukraine, on August 7. YURKO DYACHYSHYN/AFP/Getty Images
Refugees from southeastern Ukraine wait at a refugee camp in Donetsk on Wednesday, August 6. ANDREY KRONBERG/AFP/Getty Images
A pro-Russian rebel adjusts his weapon in Donetsk on August 6. Sergei Grits/AP
Men walk past a bomb crater in Donetsk on August 6. DIMITAR DILKOFF/AFP/Getty Images
A man steps out of his car as Ukrainian soldiers inspect the vehicle at a checkpoint in Debaltseve on August 6. ANATOLII STEPANOV/AFP/Getty Images
Ukrainian servicemen sit on a bus near Slovyansk, Ukraine, on Tuesday, August 5. ANATOLII STEPANOV/AFP/Getty Images
A pro-Russian separatist guards a road as Australian, Malaysian and Dutch investigators prepare to examine the crash site of Malaysia Airlines Flight 17 near the village of Rossipne, Ukraine, on August 5. U.S. and Ukrainian officials allege that a Russian-made missile shot down the plane from rebel-held territory, killing all 298 people on board. Russia and the rebel fighters deny involvement. stringer/ap
Rescue workers carry the body of a woman who was killed during a bomb shelling in Donetsk on August 5. Sergei Grits/AP
A boy stands in a hallway of a refugee hostel run by pro-Russian rebels in Donetsk on Monday, August 4. BULENT KILIC/AFP/Getty Images
Ukrainian servicemen from the Donbass volunteer battalion clean their guns Sunday, August 3, in Popasna, Ukraine. ANATOLII STEPANOV/AFP/Getty Images
Ukrainian soldiers fire shells toward rebel positions near Pervomaysk, Ukraine, on Saturday, August 2. IVAN BOBERSKYY/epa/LANDOV
Ukrainian troops patrol near the village of Novoselovka on Thursday, July 31. GENYA SAVILOV/AFP/Getty Images