Ukraine President Petro Poroshenko appealed to Russia's Vladimir Putin while Washington threatened tougher measures should Moscow fail to rein in separatists mounting a new offensive in the east of the ex-Soviet republic.
Russia's War Against Ukraine
Agence France-Presse: Poroshenko and US press Putin on Ukraine violence
Ukrainian President Petro Poroshenko speaks during a session of the World Economic Forum annual meeting on Jan. 21 in Davos.
