The North Atlantic Treaty Organization (NATO) on Monday launched the largest military air exercise in its 74-year history with more than 250 aircraft and 10,000 participants from 25 nations.

According to Germany's Federal Ministry of Defense, the flight area covers the airspace over the North Sea of Germany and the Baltic Sea, as well as northeast and south of Germany.

Hosted by Germany, the Air Defender 23 drills take place from June 12 to 23. They are aimed at enhancing the transatlantic alliance's deterrence capabilities against Russia as well as strategic collaboration among its members, according to Wei Dongxu, a military observer from CRI News Radio.

Another purpose is to "create an atmosphere" for next month's NATO summit in Vilnius, Lithuania, said Wei. It is reported that a detailed operational plan against Russia may be adopted at the summit.

Troops participating in the drills began arriving in Europe on May 29 and operations were planned to be carried out from Iceland to Romania, with most flights taking place over three regions of Germany and the North Sea. Quick-turn missions are also scheduled on remote airfields in Eastern Europe.

About half the assets belong to the U.S., which sent some 100 aircraft to Europe, with its reserve Air National Guard providing most of them. The U.S. media agency Air Force Times last week called it "an unusual show of force for the part-time component."

Sweden, which seeks to become a NATO member, and Japan will also take part in the military exercises.

Lieutenant General Ingo Gerhartz of the German Air Force, which is coordinating the exercise, said in a news conference ahead of the exercise that it intends to show that NATO territory is their red line as they were prepared to defend every centimeter of it. 

"But we won't, for example, conduct any flights toward Kaliningrad."

Kaliningrad is a Russian enclave located on the Baltic Sea between Poland and Lithuania.

"So this is intended to be defensive," Gerhartz added.

Although NATO has claimed the drills to be "defensive," they are essentially targeted at rehearsing the rapid assembly and long-range systemic operations among its members' air forces, according to Wei.

As Germany is an important air hub with large facilities at its civilian airports and air bases that can provide strong support and security for the assembly of large numbers of military aircraft, NATO will probably conduct troop build-up, ammunition loading and fuel resupply here and then deliver soldiers for long-distance combat if it wants to launch large-scale air strikes, he said.

While noting the exercise goes beyond deterrence, Lieutenant General Michael A Loh, director of the U.S. Air National Guard, said on June 7 that "this is now putting the alliance together quickly, with a credible force, to make sure that if Russia ever lines up on the NATO border, we're ready to go."

"The exercise is clearly aimed at Russia and NATO is doing everything possible to put pressure on Russia," Wei said. He also said that in the face of NATO's aggressive military exercises, Russia will inevitably demonstrate its ability to counterattack.

Criticism from peace activists, environmentalists

The military exercise received criticism from many peace activists and environmentalists.

Around 300 people staged a protest in front of the Wunstorf Air Base on Saturday, saying this exercise is a "totally wrong signal," which could lead to further escalation of the Ukraine crisis.

On Sunday, about 150 people held a demonstration in Brandenburg, setting up a huge peace sign on a mountain and calling for an end to all acts that could fan the flames of war.

"The Air Defender 23 is an irresponsible game of playing with fire," said a representative, urging the German government to take serious diplomatic measures to end the Ukraine crisis instead of continuing to resort to military threats and arms expansion.

Environmentalists said the roughly 2,000 flights during the exercise will have a damaging effect on the climate, while the noise will have a severe negative impact on animals.