Obama backs interim Ukraine PM, rebukes Putin

President Barack Obama, meeting with Ukraine’s prime minister on Wednesday, promised to defend Ukrainian sovereignty against incursions from Russia, as a Senate panel passed legislation to offer support to the nation in transition.

Obama said after meeting interim Prime Minister Arseniy Yatsenyuk that he hoped U.S. diplomacy with Moscow over the next few days could cause a "rethinking" of plans for a secession referendum set for Sunday in Ukraine’s pro-Russia Crimea region.

Obama said that Russia had infringed on international law with its incursion into Ukraine, and he warned that if Russian President Vladimir Putin did not change course he would face "costs" from the U.S. and the international community, which has already threatened economic sanctions.

Obama told Yatsenyuk in the Oval Office — in a visit intended to confer symbolic legitimacy on the Kiev government — that he had been impressed by the courage of the people of Ukraine during the ouster last month of President Viktor Yanukovich and the political turmoil that followed.

"We have been very clear that we consider the Russian incursion into Crimea ... to be a violation of international law," Obama said.

"We have been very firm in saying that we will stand with Ukraine and the Ukrainian people in ensuring that territorial integrity and sovereignty is maintained," he said.

Yatsenyuk told reporters in the Oval Office that Ukraine would "never surrender" in its fight for territorial integrity, but also that it wanted to be a good partner to Russia.

Obama said the United States would not recognize the results of the referendum in Crimea on joining Russia.

He criticized the vote as a "patched-together" exercise — but he hinted that he hoped talks between Secretary of State John Kerry and his Russian counterpart, Sergei Lavrov, later this week in London could change the situation.

"My hope is that, as a consequence of diplomatic efforts over the next several days, that there will be a rethinking of the process that has been put forward," he said.

Also Wednesday, a Senate panel advanced significant U.S. sanctions on Russia in a bid to pressure Putin to pull Russian troops out of Crimea.

The Senate Foreign Relations Committee passed the bill in a 14–3 vote.

It authorizes $1 billion in loan guarantees to Ukraine's new government, and allows the Obama administration to impose economic penalties on Russian officials responsible for the intervention in Crimea or culpable of gross corruption.

All Democrats supported the measure. Republican objections include the question of how the U.S. will pay for the loan guarantees, and provisions in the bill expanding the lending authority of the International Monetary Fund.

House Republicans are pushing their own bill.

Al Jazeera and wire services