A woman holds a sign in a protest against Russian military intervention in the Crimea region of Ukraine, on March 2, 2014, in New York City.
The United States has suspended military cooperation with Russia because of its military intervention in Ukraine, the Pentagon said on 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, Mr Kirby said.
The United States is closely monitoring the crisis and calls on "Russian forces in Crimea to return to their bases, as required under the agreements governing the Russia Black Sea Fleet," he said.
Mr 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.
American and Russian armed forces hold dozens of training events, exchanges and meetings a year as part of an effort to improve relations and defuse potential misunderstandings.
Russian officers took part in an airline hostage rescue exercise scenario with US and Canadian air commanders in 2012.
The US military has relied on Moscow's cooperation in recent years to ferry equipment and supplies across Russian territory to and from Afghanistan.