The United States suspended military cooperation with Russia over the latest developments in Ukraine, as Secretary of State John Kerry headed to Kiev.

The United States suspended military cooperation with Russia over the latest developments in Ukraine, as Secretary of State John Kerry headed to Kiev.

"We have, in light of recent events in Ukraine, put on hold all military-to-military engagements between the United States and Russia," Pentagon spokesman Rear Admiral John Kirby said in a statement Monday.

The suspension of the post-Cold War cooperation covers exercises, bilateral meetings, port visits and planning conferences, Kirby added.

Kirby stressed that the suspended system had been "developed over the past few years to increase transparency, build understanding, and reduce the risk of military miscalculation".

The crisis now threatens to blow up into the biggest test for global diplomacy -- and relations between Moscow and the West -- since the fall of the Berlin Wall in 1989.

Meanwhile, the pro-Western interim officials are to meet Kerry, who will reaffirm the United States' strong support for Ukrainian sovereignty, independence, territorial integrity", the US State Department said.

NATO is also to hold an urgent meeting on Tuesday at Poland's request in order to discuss the current crisis in Ukraine.