Major military exercises involving 30,000 NATO troops and partner countries kicked off in Norway on Monday as tensions escalate between the West and Russia over the Ukraine war.

Cold Response 2022, planned long before Moscow's invasion of Ukraine, aims to test how Norway would manage Allied reinforcements on its soil, in line with Article 5 of NATO's charter which requires member states to come to the aid of another member state under attack.

"It's a defensive exercise", said General Yngve Odlo, in charge of Cold Response.

"It's not a military operation with an offensive purpose", he told television channel TV2.

Organised every two years, the naval, air and ground drills are held over vast swathes of Norway's territory, including above the Arctic Circle.

They will however stay several hundred kilometres (miles) away from Norway's border with Russia.

Russia declined Norway's invitation to send observers.

"Any build-up of NATO military capabilities near Russia's borders does not help to strengthen security in the region", Russia's embassy in Norway told AFP last week.

Russia "has the capacity out there to follow (the exercise) in an entirely legitimate manner", Odlo said.

"I really hope they respect existing agreements", he added.

As during previous editions of the exercise, neighbouring Sweden and Finland, which are military non-aligned but increasingly close partners of NATO, will also participate in Cold Response.

Russia's invasion has renewed debate in the two Nordic countries about possible NATO membership.

Some 200 aircraft and 50 vessels are also taking part in the manoeuvres, which last until April 1.

The exercise began Monday with naval operations and the deployment on land of part of NATO's rapid reaction force.