Ukraine’s interim President Olexander Turchynov says he has ordered the withdrawal of armed forces from Crimea.
The decision was taken because of Russian threats to the lives of military staff and their families, the president announced.
A Ukrainian defence official has told the BBC that every Crimean military base is now under Russian control.
Earlier this month, Russia annexed Crimea after a referendum which Ukraine and the West considered illegal.
The G7 group of industrialised countries is to consider a collective response to the crisis during talks in The Hague.
G7 leaders are meeting on the sidelines of a long-planned summit on global threats to nuclear security.
Speaking ahead of the talks, US President Barack Obama said Europe and America were united in their support of the Ukrainian government and its people
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