Russia is to alter its military doctrine as a result of the Ukraine crisis and Nato's presence in eastern Europe, a top Russian official says.
Mikhail Popov, a Kremlin adviser, said that deteriorating relations with the US and Nato would be reflected in the updated military strategy, reports GHN based on BBC.
Nato said on Monday it would boost its presence in eastern Europe to protect its members.
Ukrainian troops are battling pro-Russian rebels in east Ukraine.
Ukraine's defence minister on Monday accused Russia of launching a "great war" that could claim tens of thousands of lives - claims dismissed by Russia, which denies actively supporting the rebels.
'Aggravating tensions'
Mr Popov, deputy secretary of Russia's National Security Council, told Russia's RIA news agency that "the military infrastructure of Nato member states" was "getting closer to [Russian] borders, including via enlargement".
Nato's actions were one of the key "external threats" to Russia, he said.
"Nato's planned action... is evidence of the desire of US and Nato leaders to continue their policy of aggravating tensions with Russia", Mr Popov said.