NATO will begin its largest-ever air exercise on Monday. 

The series of aerial manoeuvres 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 NATO members and partner states, including Japan and Sweden.  

Up to 10,000 people will take part in the exercises, which are intended to strengthen interoperability and protection against drones and cruise missiles in the event of an attack on cities, airports or ports located on NATO territory.

The drill was designed in 2018, partly in response to Russia's 2014 annexation of Crimea, though it's not specifically targeting "anyone", said Army Chief General Ingo Gerhartz of the German Air Force. 

Message to Putin

NATO is determined to defend "every centimetre" of its territory, said Gerhartz. 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.

Yet the manoeuvres 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. 

"By synchronising ourselves, we multiply our strength."