U.S. President Barack Obama warned Russia again Wednesday that the West will "apply costs" to Moscow if it continues to interfere in the affairs of Ukraine.
Mr. Obama spoke at the White House alongside interim Ukrainian Prime Minister Arseniy Yatsenyuk. He told his guest "we will stand with Ukraine."
The president referred to Russia's military presence in Ukraine's Crimean peninsula as a threat to Ukraine's territorial integrity and sovereignty. He also said Washington "completely rejects" Sunday's planned Russia-backed referendum on whether to secede from Ukraine. He said the vote, "patched together in a few weeks," is a violation of international law.
For his part, Yatsenyuk thanked Washington for its support, and said his government is "absolutely ready and willing" for talks with Moscow. But said Ukraine] will never surrender. He also said his government is preparing to sign an association agreement with the European Union later this month.
Meanwhile, U.S. Senator John McCain is set to lead a bipartisan delegation to Kyiv Thursday. A spokesman described the visit as a show of congressional support for the interim government, "and for the Ukrainian people's aspirations for freedom, democracy and territorial integrity."
The visit overlaps an emergency meeting between U.S. Secretary of State John Kerry and his Russian counterpart, Sergei Lavrov, Friday in London.
Republican McCain and his Senate Democratic colleague Christopher Murphy visited Kyiv in December, at the height of anti-government protests that eventually forced pro-Russian President Viktor Yanukovych to flee the country.
Earlier Wednesday, leaders of the Group of Seven leading industrialized nations called on Russia to, in their words, "cease all efforts to change the status of Crimea contrary to Ukrainian law."
The G7 -- which includes Britain, Canada, France, Germany, Italy, Japan and the United States -- also said it will not recognize the referendum's outcome.
In Berlin, German Chancellor Angela Merkel said the European Union will impose sanctions on Russia if it does not move to set up a contact group to discuss the Crimea crisis.