The Russian defense ministry said military drills involving the Baltic Sea fleet, the air force and paratroopers were under way in Kaliningrad, a Russian exclave sandwiched between EU and NATO members Poland and Lithuania.
"The manoeuvres are taking place just as the international games Saber Strike-2014 and Baltops-2014 began in Europe," the defense ministry said.
"The number of personnel involved in the Kaliningrad manoeuvres as well as defense ministry hardware are comparable with the number of personnel, weapons and military equipment involved in the drills conducted by NATO member countries on the border."
Around 4,700 troops and 800 military vehicles from 10 countries including Britain, Canada and the United States are participating in the Sabre Strike exercises near the Latvian capital Riga.
Russia was quick to object to the drills, which it described as "act of aggression" and which were due to move to neighbouring Lithuania today.
Russian Foreign Minister Sergei Lavrov said yesterday that NATO eastward expansion was counterproductive, saying all countries had an obligation not to beef up security at the expense of others.