Russia on Thursday kicked off a massive mobilization of military forces expected to be the largest exercise since the Cold War. The war games have triggered unease among U.S. officials and their allies in Eastern Europe, NBC News reported.
Land, sea and air units will be taking part in the exercise across a huge area encompassing western Russia, Belarus, the Baltic Sea and the Russian exclave of Kaliningrad.
Moscow says fewer than 13,000 troops are participating, meaning they don't have to invite international observers. But NATO members and Western military experts believe as many as 100,000 troops may be involved in the drills.
But analysts don't believe that Russia is about to launch a war.
"NATO remains calm and vigilant, and committed to keeping Estonia and all our allies safe," NATO Secretary General Jens Stoltenberg said last week in Estonia, one of the tiny Baltic nations that borders Russia and often worries about undue influence from Moscow.