US Vice President Joe Biden has indicated the possibility of additional sanctions against Russia over the failed ceasefire talks in Ukraine.
Ukrainian President Petro Poroshenko held phone talks with Biden on Thursday.
White House sources say Poroshenko told Biden that the Kremlin and pro-Russian separatists in Ukraine had refused all of his multiple proposals for venues to negotiate a ceasefire.
Biden told Poroshenko that the United States and its partners in the international community are discussing the need to hold Russia accountable for its continued support for the separatists.
Observers say they may be discussing additional sanctions against Russia.
The 2 men agreed that Ukrainian soldiers held captive by the separatists should be released before implementing a ceasefire. They also agreed that the Organization for Security and Cooperation in Europe should monitor the border between Ukraine and Russia.
Last week, Poroshenko told Biden that Ukraine is ready to halt the fighting and start ceasefire negotiations with the separatists if they lay down their weapons and meet other conditions.
Jul. 11, 2014 - Updated 02:44 UTC