Sweden and Finland have formally submitted their applications to join Nato, in one of the biggest geopolitical consequences to date of Russia’s invasion of Ukraine.

The Nato secretary general, Jens Stoltenberg, personally accepted the Nordic neighbours’ membership applications at the headquarters of the 30-member, US-led defensive military alliance in Haren, in the north-east of Brussels.

“I warmly welcome the requests by Finland and Sweden to join Nato. You are our closest partners,” Stoltenberg said, hailing the occasion as “a historic step” and “a good day at a critical time for our safety”.