By Associated Press and Francesca Chambers Vice President Joe Biden warned on Tuesday 'it's time for Russia to stop talking and start acting' to reduce tension in Ukraine. Standing alongside acting Ukrainian Prime Minister Arseniy Yatsenyuk in Kiev, Ukraine, Biden called on Moscow to encourage masked, pro-Russia separatists in eastern Ukraine to vacate illegally occupied government buildings and checkpoints, accept amnesty and 'address their grievances politically.' 'We have been clear that more proactive behavior by Russia will lead to more costs and greater isolation,' the Vice President said. Scroll down for video Vice President Joe Biden (left) and  acting Ukrainian Prime Minister Arseniy Yatsenyuk (right) held a press conference on Tuesday after meeting privately in Kiev, Ukraine. During the meeting the Biden offered the country additional support to help it get - and stay - on the right track
@highlight
Vice President Joe Biden  and acting Ukrainian Prime Minister Arseniy Yatsenyuk held a joint press conference in Kiev, Ukraine, on Tuesday
@highlight
At the press conference Biden called on Russia to encourage masked separatists in eastern Ukraine to vacate illegally occupied government buildings and checkpoints
@highlight
The pro-Russian separatists are in violation of an agreement signed last week by the U.S., Russia and the European Union to deescalate the situation in Ukraine
@highlight
The Vice President did not say what additional costs Russia would face if it did not use its influence to convince the pro-Russian separatists to back down
@highlight
Biden's vague threat drew the ire of Senator John McCain, who asked, 'Or else what?'
@highlight
The Vice President is now on his way back to Washington, D.C. from Ukraine
meeting in front of the press with nine @placeholder legislators from the
united as one nation, although he said @placeholder has a big difference.