Ukraine crisis: Obama urges Putin to pull troops back
US President Barack Obama has told his Russian counterpart Vladimir Putin that Russia has flouted international law by sending troops to Ukraine.
In a 90-minute telephone conversation, Mr Obama urged the Russian leader to pull forces back to bases in Crimea.
Mr Putin responded by saying that Moscow reserves the right to protect its interests and those of Russian speakers in Ukraine, the Kremlin said.
Meanwhile, Canada has recalled its ambassador to Moscow for consultations.
Canadian Prime Minister Stephen Harper said he was also suspending Canada's preparations for a G8 summit in the Russian resort of Sochi in June.
Ukraine says it has put its army on full combat alert after Russia's parliament approved the deployment of Russian troops.
Acting President Olexander Turchynov said he had also stepped up security at key sites, including nuclear plants.