Ammon News - Reuters - Russia and the US are still stuck in a stalemate on Ukraine but relations between the two countries should not be sacrificed because of their differences, Vladimir Putin has said after a phone call with Barack Obama.

President Putin's remarks were carried in a Kremlin statement issued on Friday, following the Thursday night telephone call with President Obama, the Reuters news agency reported.

"The discussion revealed the differences in the approaches and assessments of the crisis and current situation," the statement said.

During the one-hour call the US leader urged his Russian counterpart to engage with diplomatic efforts to defuse a crisis that began with anti-government protests in November and this week escalated with a threat of secession in the strategically-important peninsula of Crimea after armed men seized government buildings and military installations.

On Thursday, Crimea's parliament voted unanimously in favour of joining the Russian Federation. A referendum, asking whether the peninsula should retain ties with Kiev or join the federation, is due to take place on March 16.

Political stalemate

Ukraine, together with its American and European allies, accuses Russia of carrying out a military invasion and wants Moscow to withdraw its forces. Russian politicians say there is a need to protect Russian-speaking citizens who live in the eastern European country. In addition, Moscow says it does not recognise the interim government in Kiev, formed after the ousting of Viktor Yanukovich, and has so far refused to engage with it, saying Yanukovich is still the legitimate leader.

"Russia cannot ignore calls for help in this matter and it acts accordingly, in full compliance with the international law," the Putin statement read.

"(He) stressed the paramount importance of Russian-American relations to ensure stability and security in the world. These relations should not be sacrificed for individual differences, albeit very important ones, over international problems."

It was the leaders' second call in six days regarding the deteriorating political situation in Ukraine.

Earlier on Thursday, Obama issued an executive order authorising sanctions against "individuals and entities responsible for activities undermining democratic processes or institutions in Ukraine."

'Unusual and extraordinary'

About 11,000 pro-Russian troops are in control of Crimea and have blocked access to all Ukrainian military bases that have not yet surrendered, according to the regional leader Sergei Aksyonov.

All or most of those troops are believed to be Russian, even though Moscow has repeatedly denied sending them, and some of those troops blocked military observers from the Organisation for Security and Co-operation in Europe from entering Crimea, the group said on Thursday.

Obama on Thursday called Russia's involvement in Crimea "an unusual and extraordinary threat to the national security and foreign policy of the United States".

During the call with Putin, Obama outlined the terms of a compromise - what US diplomats are calling an "off-ramp" settlement - that his officials are promoting.

Under the terms of the deal, Russia would withdraw troops from bases in Crimea, allow international monitors in to ensure the rights of ethnic Russians are respected and agree to direct talks with Ukraine officials.

Chris Bellamy, professor of maritime security at the Greenwich Maritime Institute, told Al Jazeera it was possible but unlikely that Ukraine would lose Crimea.

"Crimea has only been part of Ukraine since 1954. Fifty percent of its population is Russian, 24 percent is Ukrainian and 12 percent are Crimean Tatar...there’s very much a Russian majority," he said.

"But I don’t think the world community likes to break up countries very much. I think giving Crimea back to Russia, while it’s an option, it’s not likely."