On Monday, Russia's parliamentary speaker said Moscow had the "right" to launch military action in Ukraine. However, the crisis had not escalated to that point yet, said Sergei Naryshkin.

"The decision by the Federal Council (upper house) just gives the right and this right can be used in case it is necessary. But currently [it] is not necessary," Naryshkin on Russian state television.

Naryshkin's comment followed closely after Russian news agency Interfax said the country's Black Sea Fleet had issued an ultimatum to Ukrainian forces in the Crimean peninsula to surrender by 5 a.m. local time (0300 UTC) on Tuesday. The Black Sea Fleet has since it had issued a deadline with the threat of an assault, according to Interfax, who had originally been quoting an unnamed Ukrainian official.

Following the European foreign ministers' meeting in Brussels on Monday evening, EU foreign minister Catherine Ashton called on Russia to withdraw its troops. She added that the EU would consider "targeted measures" against Moscow if it did not show steps of de-escalation.

"We want to see this situation resolved peacefully," Ashton said.

EU foreign ministers are due to meet on March 6 for an extraordinary summit.

Russia requests UN Security Council session

Meanwhile, Russia has requested an extraordinary UN Security Council session to deliberate on Ukraine. The meeting is to take place on Monday at 3:30 p.m. local New York time (2030 UTC).

According to US sources, Russian troops are now in control of Crimea, with more than 6,000 troops stationed on the Black Sea peninsula.video#

Russian forces had surrounded several Ukrainian army bases in Crimea on Sunday, a day after President Vladimir Putin won approval from parliament to use military force to protect local ethnic Russian citizens.

Ukraine's interim Prime Minister Arseniy Yatsenyuk responded by calling up all military reservists, saying Moscow had put the two countries "on the brink of disaster."

"This is not a threat: this is actually the declaration of war to my country," he said in Kyiv.

Lavrov defends Moscow

The threat of a military strike on Ukrainian forces coincided with a session of the 25th Human Rights Council in Geneva, where Russian Foreign Minister Sergei Lavrov defended Moscow's actions of recent days. Lavrov said the troops would remain on the Crimean peninsula "until the normalization of the political situation."

He also called NATO's criticism of the events as a move that will only weaken its only goals.

"We believe that such a position will not help stabilize the situation in Ukraine and only encourages those forces that would like to use the current events to acheive their irresponsible politicals goals," Lavrov said.

The Russian foreign minister also criticized warnings of sanctions and boycotts over Moscow's role in the escalating crisis, accusing the West of putting its own "geopolitical calculations" ahead of the fate of the Ukrainian people.

"We call for a responsible approach, to put aside geopolitical calculations, and above all to put the interests of the Ukrainian people first," he said.

German Chancellor Angela Merkel and Foreign Minister Frank-Walter Steinmeier have attempted to maintain calm diplomatic ties with Putin. On Sunday, the chancellor spoke with the Russian president, who reportedly agreed to support a "fact-finding" mission to calm escalating tensions between Moscow and Kyiv.

Russia 'defending' Russian citizens

Despite stern warnings from the West, the Russian foreign minister persisted with his country's insistence that it was defending Russian citizens and compatriots in Ukraine.

"The victors intend to make use of the fruits of their victory to attack human rights and fundamental freedoms…of minorities," Lavrov said. He added that "radicals" were in control of the cities and were limiting the rights of "linguistics minorities."

The linguistic and ethnic makeup of Ukraine - particularly in its southern Crimean peninsula - have emerged as an explosive issue that could undermine efforts to stabilize the country since the dramatic shift in leadership in Kyiv at the end of February.

Last week, while the interim government worked to keep Ukraine's economy afloat, representatives of Crimea's majority Russian-speaking population clashed with its historically Muslim ethnic-Tatar citizens, who support Kyiv.

The pro-Russia contingent then took over government buildings in Crimea and then proposed a referendum on the region's status. Several days later, Moscow, which already has a naval base in Crimea, deployed more soldiers to the area. The move sparked an international diplomatic crisis.

Lavrov's reference to "linguistic minorities" also stems from a controversial move by the Ukrainain parliament last week to repeal a 2012 language law. The vote sought to scrap the legislation, which allows local governments to recognize more than one official language if at least 10 percent of its population speaks another language, such as Russian. However, interim President Oleksandr Yatsenyuk vetoed the bill on Friday, allowing the language law to remain in force.

Allies begin scrapping deals with Moscow

Russian President Vladimir Putin's refusal to back down from the current crisis in Ukraine has prompted Western governments and alliances to suspend - or threaten to suspend - potentially lucrative deals with Russia.

EU foreign ministers agreed on Monday to shelve talks on a long-awaited visa deal for Russian citizens, according to a draft statement.

"The EU has decided to suspend bilateral talks with Russian authorities on visa matters, as well as on the new agreement," the draft EU statement said.

The Group of Eight Nations (G8) also condemned Russia's actions, according to a White House statement, in which the leaders referred to themselves symbolically as the 'G7.'

As a consequence of the military aggression in Crimea, the group suspended preparations for June's G8 summit in Sochi Russia, "until the environment comes back where the G8 is able to have meaningful discussion."

Russian role in Czech reactor project in doubt

A multi-billion-dollar contract to build two nuclear reactions in the Czech Republic had also been thrown into doubt, according to eastern European country's defense minister.

Czech Republic Defense Minister Martin Stropnicky said he could "hardly imagine" Russia would win the $10-billion contract given the current circumstances in Ukraine.

"Russia has disappeared from the group of predictable,democratic countries. What it is doing is unacceptable," Stropnicky said.

kms/ipj (AP, AFP, Reuters, dpa)