US President Joe Biden announced a significant strengthening of US force posture in Europe as he began a two-day NATO summit in Madrid.

Speaking alongside the NATO secretary-general, Biden listed new troop movements, equipment shipments and military installations meant to demonstrate the importance of security as Russia's war in Ukraine grinds on, CNN reported.

“The United States and our allies are stepping up and proving that NATO is needed now more than ever, and is as important as it ever has been,” Biden said.

He said the US would establish a permanent headquarters for the Fifth Army Corps in Poland, maintain an additional rotational brigade of 3,000 troops in Romania, enhance rotational deployments to the Baltic states, send two additional F-35 fighter jet squadrons to the United Kingdom and station additional air defence and other capabilities in Germany and Italy.

“Together with our allies, we are going to make sure that NATO is ready to meet threats from all directions across every domain, land, air, and sea,” Biden said.

He praised the breakthrough diplomacy with Turkey that has set the stage for Finland and Sweden – two longtime neutral countries – to join NATO, saying it sent a clear signal to Russia that the alliance was united and growing.

“Their decision to move away from neutrality and the tradition of neutrality to join the NATO alliance is going to make us stronger and more secure and NATO stronger,” he said. “We are sending an unmistakable message in my view… that NATO is strong, united, and the steps we are taking during this summit are going to further augment our collective strength.”

Biden said the two Scandinavian countries’ expected accession was a sign Putin's aims had backfired.

“I said Putin was looking for the Finlandization of Europe. He's going to get the NATOization of Europe, and that is exactly what he did not want, that's exactly what needs to be done to guarantee security for Europe. And I think it’s necessary,” he said.