BRUSSELS -- NATO has launched its largest military exercise since the collapse of the Soviet Union, mustering tens of thousands of troops in what the head of the Western alliance called a "strong display" of its capability, unity, and resolve at a time of growing danger in Europe.
The main phase of the exercise Trident Juncture -- involving military forces from all 29 NATO allies, plus partners Finland and Sweden, and stretching from the North Atlantic to the Baltic Sea -- began in Norway on October 25 and was scheduled to run for two weeks.
"This is an important day because Trident Juncture is NATO's biggest exercise since the end of the Cold War," NATO Secretary-General Jens Stoltenberg said ahead of the drills.
The exercise is drawing criticism from Moscow amid persistent tension between NATO and Russia, which seized Crimea from Ukraine in 2014 and backs separatists in an ongoing conflict in eastern Ukraine but accuses the alliance of provocative behavior near its borders.
Another source of discord is what NATO says is Russia's deployment of a missile that violates a key U.S.-Russian nuclear arms treaty and could potentially be used to target alliance members in Europe.
"Trident Juncture sends a clear message to our nations and to any potential adversary: NATO does not seek confrontation, but we stand ready to defend all allies against any threat," Stoltenberg told a news conference on October 24.
The exercise "is a strong display of our capabilities and our resolve to work together," he said.
Without mentioning Russia by name, he said that "Europe's security environment has significantly deteriorated" in recent years and that NATO has responded with the biggest adaptation of our collective defense since the end of the Cold War. Trident Juncture demonstrates that adaptation."
"Trident Juncture will include around 65 ships, 250 aircraft, 10,000 vehicles, and 50,000 personnel," Stoltenberg said of the exercise, which will run in two phases.
"It is ambitious and it is demanding," he said.
The live-field exercise is set to run from from October 25 to November 7, while a command post exercise is to follow between November 14-23.
Moscow has frequently said that it views NATO's enlargement to include former Warsaw Pact countries and the Baltic states since the 1991 Soviet collapse as provocative, and Russia and NATO have repeatedly accused each other of aggressive action repeatedly in recent years.
Russia held large military exercises called Zapad-2017 (West-2017) in September 2017 in its western regions jointly with Belarus, which also borders several NATO countries, and last month conducted massive drills across its central and eastern regions.
The Defense Ministry said the weeklong Vostok-2018 (East-2018) war games involved some 300,000 personnel -- twice as many as the biggest Soviet maneuvers of the Cold War era.
Speaking at a joint panel of the Russian and Belarusian defense ministries in Minsk on October 24, Russian Defense Minister Sergei Shoigu said that "the scale of [NATO] operational and combat training near our borders is expanding, its intensity is growing. The bloc's member states are practicing the objectives of conducting offensive combat actions."
Despite criticizing the NATO exercise, Russia has accepted an invitation to send observers to Norway, a move that Stoltenberg welcomed in the name of transparency.
"As long as they behave professionally and avoid dangerous situations and behavior, I don't think that's a problem at all that they monitor the exercise," the NATO chief said.
Describing the exercise, Stoltenberg said the personnel will be split into "South Forces" and "North Forces" that will "take turns playing the role of the fictitious aggressor and the NATO defending forces. The exercise will test our readiness to restore the sovereignty of an ally -- in this case Norway -- after an act of armed aggression.
"This scenario is fictitious but the lessons we learn will be real," he said.
Norway shares a short border with Russia in the Arctic.