Washington does not anticipate a breakthrough with Russia over the Ukraine crisis at a Geneva meeting of foreign ministers, U.S. officials said.
Thursday's meeting brings together the ministers of Russia, Ukraine, the U.S. and the EU's foreign policy chief to discuss a crisis in which Kiev is struggling to reassert its authority in eastern towns largely controlled by armed pro-Russian separatists.
With Russian troops massed on the border with Ukraine, prospects of significant progress at the four-way talks appear slim. By contrast, what President Vladimir Putin says during his annual "hotline" session with the Russian people may have far greater influence on events in Ukraine's rebellious east.
Upon arriving in Geneva on Wednesday, Ukrainian Foreign Minister Andriy Deshchytsia said there still is time for negotiations to ease tensions with Russia.
"I think that we still have a chance to de-escalate the situation using diplomatic means," he said. "And we will try hard. We are trying hard — not only Ukraine — but also the U.S. However, the time is now, not only to express concern, but to look for a more concrete and adequate response to Russia's plans and actions."
U.S. officials said it was reasonable to assume that more sanctions would be imposed against Russia if there was no progress at the meeting. Additional sanctions could come from Washington as soon as Friday.
"What I have said consistently is that each time Russia takes these kinds of steps that are designed to destabilize Ukraine and violate their sovereignty, that there are going to be consequences," President Barack Obama said Wednesday in an interview with CBS.
Deshchytsia went to Geneva with a weak hand as his government's offensive to regain control of official buildings occupied by rebels in about 10 eastern towns has made humiliatingly little progress.
Separatists flew the Russian flag on armoured vehicles taken from the Ukrainian army on Wednesday. Six of them were driven into the rebel-held town of Slovyansk to shouts of "Russia! Russia!" It was not immediately clear whether they had been captured by rebels or handed over to them by Ukrainian deserters.
Armed pro-Russia separatists also attacked a Ukraine base in the eastern city of Mariupol on Wednesday and national guard soldiers fired shots in the air to turn them back. A government statement did not say if anyone was injured in the attack.
Putin has accused the Ukrainian government of risking mass bloodshed by using its military to try to crush the rebellion in the largely Russian-speaking East.
"The sharp escalation of the conflict puts the country, in effect, on the brink of civil war," Putin told German Chancellor Angela Merkel this week, the Kremlin said.