Vice President Joe Biden has spoken to Ukraine's new president amid a major shake-up in Ukraine's beleaguered military.
Biden and President Petro Poroshenko spoke Thursday as foreign leaders try to restart peace talks. A unilateral ceasefire declared by Poroshenko expired this week after being violated repeatedly by pro-Russian separatists.
The White House says the two leaders discussed diplomatic efforts to put in place a ceasefire that would hold, be respected by separatists and supported by Russia. Biden also threatened further U.S. sanctions against Russia unless it stops supporting separatists and sending arms across the border into Ukraine.
The call comes as Poroshenko is seeking to rejuvenate Ukraine's rickety military and combat corruption by appointing a new defense minister and top general.