Foreign ministers from East and West will try to defuse the Ukraine crisis on Thursday, even as fresh violence erupted overnight in the restive east.

Thursday's talks in Geneva, Switzerland will bring the ministers of Russia, Ukraine and the United States together with the European Union's foreign policy chief to find ways out of the worst East-West crisis since the end of the Cold War - where Kiev's embattled new leaders are struggling to reassert their authority in eastern towns largely controlled by armed pro-Russian separatists.

But even as diplomats descend on Geneva, the U.S. is talking more sanctions to punish Russia. Kiev and the West believe Moscow is stirring up the unrest.

"What I've 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 and what you've already seen is the Russian economy weaker, capital fleeing out of Russia," President Barack Obama told CBS.

In an ominous echo of the events that led to Moscow's annexation of Crimea last month, the Donetsk People's Republic wants a referendum no later than May 11, the self-declared chairman of the people's council told CNN on Thursday.

The referendum will essentially ask residents which country they want to be a part of, said Denis Pushilin.

MORE at CNN.com.