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. The series of aerial maneuvers being coordinated by Germany is intended to show the strength and unity of the Western military alliance, set against the backdrop of the Ukraine war. The "Air Defender 23" exercise will run until 23 June, bringing together some 250 military aircraft from 25 members and partner states of the North Atlantic Treaty Organization, including Japan and Sweden. According to Germany's Federal Ministry of Defense, 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 US, which sent some 100 aircraft to Europe, with its reserve Air National Guard providing most of them. The US 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, 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 he added it will not send any flight "in the direction of Kaliningrad", the Russian enclave bordering NATO members Poland and Lithuania. "We are a defensive alliance and that is how this exercise is planned," insisted the general. 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 observers. 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, they said. 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. The drill was designed in 2018, partly in response to Russia's 2014 annexation of Crimea, though it's not specifically targeting "anyone", said Gerhartz. Yet the maneuvers will also aim to send a message to Russia, according to the US Ambassador in Germany, Amy Gutmann. "I would be very surprised if a world leader did not take note of what this shows in terms of the spirit of this alliance, what the strength of this alliance means, and that includes Mr. Putin," she told reporters. Russia's war against Ukraine has galvanized the US-led military alliance created nearly 75 years ago to confront the Soviet Union. Finland and Sweden — traditionally officially neutral, though closely aligned with NATO — asked to join after Russia invaded Ukraine last year. Potential travel disruption In an email seen by Euronews, Wizz Air warned customers flying from Latvia to Britain the exercise may impact multiple European airspaces. It urged flyers to check their website before traveling to the airport. "Even though these circumstances are beyond our control, we apologize for any potential inconvenience caused and we will work hard to minimise any travel disruptions." Asked about potential disruptions to civilian air travel during the exercise, General Gerhartz insisted planners would do "everything in their power" to limit flight delays or cancellations, with school holidays starting in parts of Germany. — Agencies