The State Department criticized Russia's "unacceptable" refusal to release Ukrainian pilot Nadiya Savchenko, who has been on hunger strike for almost 11 weeks.
What started out as a local protest over presidential overreach has grown into a chaotic war between Ukraine and pro-Russian separatists, all within a calendar year.
The leaders of Russia, Ukraine, Germany and France agreed to meet in Belarus on Wednesday to try to broker a peace deal for Ukraine amid escalating violence.
In an exclusive interview to air Sunday on Meet the Press, Secretary of State John Kerry says he has "no doubt" that additional assistance will be going to Ukraine.
Rocket fire kills at least 30 people in the Ukrainian city of Mariupol in the southeastern region of the country Saturday. The incident occurred just one day after Russian rebels rejected a peace deal with Ukraine.
NATO's military commander Gen. Philip Breedlove said alliance intends to re-establish contact with Russian counterparts, after months of tension over Ukraine.
Shell or mortar round hit trolleybus at stop in rebel-controlled Donetsk in eastern Ukraine. Eye witnesses counted at least six dead in and around bus.
Ukrainian President Petro Poroshenko was shouted at by angry relatives of the 100 protesters killed in Kiev's "Euromaidan" revolution at a ceremony to pay tribute to the victims.