More than 250 aircraft and 10,000 personnel began a two-week military exercise on Monday involving Nato nations and Japan, in what host nation Germany bills as the largest deployment of aircraft in the alliance’s history.

Planning for the training began in 2018. But it comes as fighting escalates on Nato’s doorstep in Ukraine, where Kyiv’s forces, backed by arms from western allies, are mounting an offensive to reclaim territory captured by Russia since the invasion ordered last year by President Vladimir V. Putin.

Officials involved in the 25-nation Nato exercise said it sends a message about the alliance’s solidarity.

“I would be pretty surprised if any world leader was not taking note of what this shows, in terms of the spirit of this alliance, which means the strength of this alliance,” Amy Gutmann, the US ambassador to Germany, told reporters last week. “That includes Putin.”

The exercise, known as Air Defender, is led by the German government and brings together the largest number of aircraft from outside Germany for a training mission since Nato was founded in 1949.

The US flew about 100 National Guard and Navy aircraft to Germany for the exercises.

The 12-day event began with an air show in Wunstorf, in northern Germany, that features cargo and refuelling planes — workhorse aircraft that have been crucial to getting weapons and supplies to Ukraine. Pilots will conduct other missions with fighter jets, the show horses of the sky, at five other bases across Germany.

The exercise comes a few weeks after the US reluctantly agreed to allow Ukrainian troops to train on, and eventually obtain, American-made F-16 fighter jets — not just for the current conflict against Russia but also as part of a longer-term deterrence strategy.

Air Force General Ingo Gerhartz of Germany, who is overseeing Air Defender, said it was not “directed at anyone”, and emphasised that no offensive scenarios would be practised. “We are a defence alliance, and so this exercise will be of a defensive nature,” General Gerhartz told reporters in Berlin.

But General Gerhartz said that when he proposed the exercise, in 2018, “the trigger for me back then was the capture, the annexation of Crimea”, the Ukrainian peninsula, by Putin four years earlier.

Since Russia’s full-scale invasion of Ukraine last year, General Gerhartz said, allies on Nato’s eastern flank, closest to Russia, “are asking for reinsurance” that the alliance will defend them in case of aggression by Moscow.

New York Times News Service