Russia yesterday said it wanted answers from Nato on its activities

in eastern Europe after the Western military alliance promised to beef up defences for its eastern members.

Meanwhile, Ukraine's Western-backed leaders yesterday blamed Russian agents and the country's ousted president of organising two days of bloodshed in February that claimed nearly 90 lives.

Russia's annexation of Ukraine's Crimea region last month has caused the deepest crisis in East-West relations since the Cold War, leading the West to impose sanctions and sparking fear President Vladimir Putin has territorial designs beyond the Black Sea peninsula with its Russian-majority population.

Nato has ordered military planners to draft measures to reassure nervous Eastern European countries - which were under

Moscow's domination until the 1989 end of the Gold War - but

stopped short of calls by Poland to base more forces there.

Russian Foreign Minister Sergei Lavrov said any increase in Nato's

permanent presence in eastern Europe would violate a 1997 treaty on Nato-Russian cooperation.

Nato military chiefs are concerned that an estimated 40,000 Russian forces near the Ukrainian border may signal plans by Putin to move beyond Crimea into eastern and southern Ukraine, which also have significant Russian-speaking populations.Lavrov Russian troops would return to their permanent bases after military exercises.

Meanwhile, NASA has cut ties with Russia except for cooperation aboard the International Space Station due to the crisis in Ukraine, the LIS space agency said.