Russian President Vladimir Putin said "the necessary conditions have been created for putting an end to the fratricidal war in Syria."
The war games include an "offensive portion... that looks to me like a rehearsal of an attack," General Curtis Scaparrotti said.
The Baltic NATO ally summoned Russia's envoy to demand an explanation, but Moscow claims the incursion was an emergency call which is being "politicized."
The Zapad drill on Europe's borders could include almost 10 times the permitted number of troops, provoking fears among NATO members.
“It is more unpredictable, and it’s more difficult,” Stoltenberg said when asked about the changes in the world over his 30-year career.
The Swedish military is kicking off its biggest exercise in almost a quarter of a century, while Russia and Belarus perform combat readiness drills nearby.
Ukraine's President Poroshenko said Moscow showed no signs of backing off from his country and recent military activity shows the Kremlin is preparing for a much bigger conflict.
The Russian Il-20 aircraft flew to and from Kaliningrad—a course Russia has defended as a "necessity."
Despite repeatedly assuring his rivals that Russia's upcoming military exercises were just that, President Vladimir Putin faces regional doubts.
The upcoming Russian drill has concerned the Baltics, but it is Moscow-ally Belarus that should be worried, Mikheil Saakashvili says.
Moscow denies harassing its neighbors and has accused the U.S. of undermining Russia's own national security.
Russia's upcoming Zapad drill was described as a "simulated attack" by Lithuania's government.
Russia's tanks are "the best in the world," army chief says ahead of Olympic-style competition with China, India and others.
NATO allies have deployed a limited number of aircraft in Romania, which borders Ukraine, to assist with its air patrols. Russia is not happy.
The British and Turkish ships dock in Odessa as Kiev warns about a regression into deadly combat.
Poland has already agreed to purchase the system, while Sweden will be next to experience it firsthand in a joint drill with U.S.
In defending Syria's government, Russia honored an old alliance and gained a new, strategic victory over NATO.
Russian jets have been caught near NATO skies twice recently.
Russian helicopters blasted their targets not far from where the U.S. and NATO allies have just begun fortifying their air defenses.
Russia's upcoming nearby drill has been described as a "simulation" for an attack on its Baltic neighbors.