By Will Dunham and Ros Krasny
WASHINGTON (Reuters) - It is not in the interest of Russia, Europe or the United States to see Ukraine split apart and it would be a "grave mistake" for Russia to send military forces into that country, President Barack Obama's national security adviser said on Sunday.
Speaking on the NBC program "Meet the Press", Susan Rice was asked about a possible scenario in which Russia would send forces into Ukraine to restore a government more friendly to Moscow.
"That would be a grave mistake. It is not in the interests of Ukraine or of Russia or of Europe or the United States to see the country split. It's in nobody's interest to see violence return and the situation escalate," Rice said.
Rice's appearance on the program provided the most extensive White House comments yet on the recent dramatic events in Ukraine.
Many in Washington regard the next few days as crucial to the fast-unfolding crisis, as the Winter Olympic Games in Sochi, Russia, end and Putin could more closely focus on the Ukrainian situation.
The State Department said on Saturday it would send its No. 2 official, Bill Burns, to Kiev this week.
Rice said the United States wants a de-escalation of the violence in Ukraine, constitutional changes, democratic elections "in very short order," and the opportunity for Ukrainians to come together in a coalition unity government.
The fluidity of Ukraine's situation is such that U.S. authorities are not sure where Russian-backed President Viktor Yanukovich has fled.
"He is in a place that will reveal itself. Yesterday we knew where he was. Today we're not so sure," Rice said.
The crisis in Ukraine reflects the conflict between those who want the country to remain aligned with Moscow and Russian President Vladimir Putin, and those seeking closer integration with Western Europe.
But Rice said those goals were not "mutually exclusive".
"There is not an inherent contradiction ... between a Ukraine that has longstanding historic and cultural ties to Russia and a modern Ukraine that wants to integrate more closely with Europe," Rice said.
On Sunday, Ukraine's parliament, exercising power since mass protests caused Yanukovich to flee, named its new speaker as acting head of state and worked to form a new government.
The European Union and Russia, vying for influence over the huge former Soviet republic on their borders, considered their next moves.
Russia, which had provided funding to Yanukovich's government, said it would keep cash on hold until it sees who is in charge.
Asked whether Putin looked at Russia's sphere of influence in Ukraine in a Cold War context, Rice said that "he may".
"But if he does, that's a pretty dated perspective that doesn't reflect where the people of Ukraine are coming from. This is not about the U.S. and Russia," Rice added.
Two key lawmakers urged the Obama administration to make clear that Ukraine's territorial integrity must be protected.
"I think the message has to be sent to him (Putin) that let the Ukrainian people determine their own future, and a partition of Ukraine ... is totally unacceptable," Republican Senator John McCain, a key Republican voice on foreign policy, told the CBS program "Face the Nation".
"And we need to act immediately to give them (Ukrainians) the economic assistance that they need, based on reforms that are gonna be required, as well. So it's gonna be tough sledding."
Bob Corker, the top Republican on the Senate Foreign Relations Committee, added in a statement: "The United States should do everything possible to ensure Ukraine remains one country and that their territorial and political integrity is maintained, allowing them the freedom to choose a future within Europe."
Earlier on Sunday, U.S. Treasury Secretary Jack Lew met his Russian counterpart, Anton Siluanov, on the sidelines of a Group of 20 meeting in Sydney to discuss the situation in Ukraine.
"Secretary Lew emphasized that the United States, working with other countries including Russia, stands ready to assist Ukraine as it implements reforms to restore economic stability and seeks to return to a path of democracy and growth," a Treasury Department official said.
(Reporting by Will Dunham and Ros Krasny; Additional reporting by Ian Chua in Sydney; Editing by Marguerita Choy and Sophie Hares)