WASHINGTON - The United States on Monday suspended all military engagements with Russia because of the crisis in Ukraine, including military exercises and port visits, as part of Washington's response to Moscow's seizure of Crimea.

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The announcement from the Pentagon came hours after President Barack Obama warned the US government will look at a series of economic and diplomatic sanctions that would isolate Moscow.

"We call on Russia to de-escalate the crisis in Ukraine and for Russian forces in Crimea to return to their bases," Pentagon spokesman Rear Admiral John Kirby said in a statement.

The US military does not take such steps lightly and took no such action, for example, last year during turmoil in Egypt that saw the army topple the country's first freely elected leader.

Military-to-military contacts help bridge gaps between nations and reduce chances of misunderstandings, officials often say.

Kirby said that although the Defense Department found "value" in military-to-military relations with Russia, "we have, in light of recent events in Ukraine, put on hold all military-to-military engagements." Its suspension also applied to bilateral military meetings and planning conferences, he said.

Despite an international outcry over actions in Ukraine, Putin has shown little sign of backing down, and Russia has built up armored vehicle presence near Crimea and staged military maneuvers in what appears to be a show of strength.

US officials have dismissed the possibility of military options, which could further escalate the standoff, and the Pentagon appeared at pains to quash any speculation the US armed forces were poised to get involved.

"Some media outlets are speculating on possible ship movements in the region. There has been no change to our military posture in Europe or the Mediterranean," Kirby said.

Kirby added US Navy units were conducting routine, previously planned operations and exercises in the region.

Special: Ukraine crisis

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