Ukrainian Prime Minister Arseny Yatseniuk has said he will go to the US this week to discuss the standoff with Russia over Ukraine's southern region of Crimea.
"I am going to the United states to hold top-level meetings on resolving the situation unfolding in our bilateral and multilateral relations," Yatseniuk said.
Barack Obama warned Russia that the West will be forced to apply a cost to Moscow if it fails to change course in its dispute with Ukraine.
The ballot paper that the people of Crimea will use in Sunday's referendum was published today
Vitali Klitschko's visit to the eastern city of Donetsk is clearly an attempt to try to ease the divisions with Ukraine.