New Ukraine government asks military assistance to United States outside the NATO area 1903141.

Biden, also visited Warsaw where he reportedly told Polish president Bronislaw Komorowski that the US had sent a dozen F-16s to a Polish base, and will expand army trainers to help the Polish army modernize.

The White House said it was also considering calls for military assistance from the Ukraine, which is not a NATO member but is thought to have asked for defence equipment.

In London, British Foreign Secretary William Hague said the U.K. was suspending military cooperation with Russia in light of the crisis over Ukraine. He said the U.K. is suspending military export licenses to Russia, has canceled naval exercises and suspended a proposed Royal Navy ship visit to Russia.

Putin has accused the West of encouraging unrest in Ukraine in order to break its historic ties with Russia, and dismissed Western criticism of the Crimean vote as illegitimate.

Russia said it sent troops to Crimea to protect Russian residents, who it said were in danger in the unrest that followed the toppling of Ukraine's pro-Russian president. A referendum in Crimea on Sunday backed union with Russia,

Addressing lawmakers in Ukraine's parliament on Monday, Olexandr Turchynov, the acting president, described Sunday's Crimean poll as illegal. He also signed a decree to mobilize volunteers and reservists.