The United States has suspended defense cooperation with Russia because of Moscow's military intervention in Ukraine, the Pentagon said Monday, urging Moscow to "de-escalate the crisis."
"We have, in light of recent events in Ukraine, put on hold all military-to-military engagements between the United States and Russia," spokesman Rear Admiral John Kirby said in a statement.
The suspension covers "exercises, bilateral meetings, port visits and planning conferences, Kirby said.
The United States is closely monitoring the situation in Ukraine, he said.
"We call on Russia to de-escalate the crisis in Ukraine and for Russian forces in Crimea to return to their bases, as required under the agreements governing the Russia Black Sea Fleet," he said.
Kirby also stressed that US forces have not altered their presence in the Black Sea or elsewhere in response to the crisis.
"There has been no change to our military posture in Europe or the Mediterranean," he said.
Naval forces continue to carry out "routine, previously planned operations and exercises with allies and partners in the region," he said.
The only US naval ship currently in the Black Sea is the frigate USS Taylor, which is undergoing repairs at the Turkish port of Samsun after running aground, officials said. The commander of the ship was sacked over the incident.
The United Sates has condemned Russia for mobilising forces in Ukraine's Crimean peninsula after popular protests ousted the country's pro-Russian president. But US officials have made clear President Barack Obama is not contemplating a military confrontation with Russia.
As part of a long-running effort to bolster relations and defuse potential misunderstandings, the American and Russian armed forces hold dozens of training events, port visits, exchanges and meetings every year.
Russian officers took part in an airline hostage rescue exercise scenario with US and Canadian air commanders in 2012 and the chief of the US Navy hosted his counterpart for talks last year.
The US military has relied on Moscow's cooperation in recent years to ferry equipment and supplies across Russian territory to and from Afghanistan.
Discuss ways to 'further isolate'
President Barack Obama met for over two hours on Monday with his national security advisors and discussed ways the United States and its allies could "further isolate" Russia over its military intervention in Ukraine, a White House official said.
The group discussed ways to "reinforce that the Russians still have an opportunity to take immediate steps to de-escalate the situation or they face further political and economic repercussions from the international community," the official said about the meeting.
"The president will continue to receive regular updates on the situation, and to remain in close contact with his foreign counterparts," the official said.