MADRID -- President Joe Biden said Wednesday the U.S. will significantly expand its military presence in Europe, the latest example of how Russia's invasion of Ukraine has reshaped plans for the continent's security and prompted a reinvestment in NATO.
Among the changes will be a permanent U.S. garrison in Poland, for the first time creating an enduring American foothold on the alliance's eastern flank. Biden also said the U.S. would send two additional squadrons of F-35 fighter jets to the United Kingdom and more air defenses and other capabilities to Germany and Italy.
"The United States will enhance our force posture in Europe and respond to the changing security environment as well as strengthening our collective security," he said during a meeting with NATO Secretary-General Jens Stoltenberg at the alliance's annual leaders summit in Madrid.
The dry language belied the dramatic shift under way as the U.S. prepares to keep 100,000 troops in Europe for the "foreseeable future," up from 80,000 before the war in Ukraine began.
Stoltenberg, who earlier Wednesday said the alliance was facing its biggest challenge since World War II because of Russia's invasion of Ukraine, welcomed Biden's announcement.
"This really demonstrates your decisive leadership and strength in the trans-Atlantic bond," Stoltenberg said, thanking Biden for "unwavering support from you and from the United States to Ukraine."
The expanding U.S. military presence is still far short of its numbers during the Cold War, when roughly 300,000 American troops, on average, were stationed in the region. But it signals a renewed focus on European security. And the U.S. announcement is bolstered by other commitments made by allies on the continent.
NATO plans to increase the size of its rapid reaction force from 40,000 to 300,000 troops by next year. Although the troops would be based in their home countries, they would be ready to deploy further east, where the alliance will stockpile equipment and ammunition.
Max Bergmann, a former State Department official who is director of the Europe Program at the Center for Strategic and International Studies, said this is "a defining year" for the continent and the alliance.
"It's a hugely significant turning point, and one that historians are going to look back on," he said.
He described the decision to shift U.S. forces further east as particularly noteworthy.
"We're going to defend the line," he said. "We're not just going to have a tripwire. We're not going to cede anything."
Biden said the U.S. would step up its temporary deployments of troops to Romania and the Baltic region, in addition to permanently stationing the U.S. Army V Corps forward command in Poland.
Celeste Wallander, an assistant U.S. secretary of defense for international affairs, told reporters that having a long-term presence in Poland will be key to helping NATO navigate the changed security environment in Europe caused by Russia's invasion. The U.S. supplies the bulk of NATO's military power.
Poland's President Andrzej Duda, present in Madrid, said on Twitter that the permanent presence of U.S. military command structure was an "extremely important decision" and a "decision that we have been waiting for."
U.S. officials emphasized that the permanent basing applied only to headquarters units, not combat troops, and was therefore consistent with a 1997 agreement between NATO and Russia in which the alliance agreed not to permanently base combat troops in Eastern Europe as it aimed to build more constructive ties in the post-Cold War environment.
The combat units Biden is sending to Romania and the Baltic region are on rotational deployments, rather than permanent assignment, to remain in compliance with that agreement.
"There has been no communication with Moscow about these changes, nor is there a requirement to do that," said John Kirby, a spokesman for Biden's National Security Council.
Biden announced on Tuesday after arriving for the summit that the U.S. would base two additional destroyers at its naval base in Rota, Spain, bringing the total number to six.
Biden predicted that meetings this week would make for a "history-making summit" as leaders were set to approve a new strategic framework, announce a range of steps to boost their defense spending and capabilities, and clear the way for historically neutral Finland and Sweden to join NATO.
Biden said Russian President Vladimir Putin thought NATO members would splinter after he invaded Ukraine, but got the opposite response.
"Putin was looking for the Finland-ization of Europe," Biden said. "You're gonna get the NATO-ization of Europe. And that's exactly what he didn't want, but exactly what needs to be done to guarantee security for Europe."
Turkey, the last remaining holdout to approve the Nordic countries' accession into NATO, reached an agreement late Tuesday to support adding them to the 30-nation alliance.
While the White House said the U.S. was not a direct party to the negotiations, a senior administration official said Biden spoke with Turkish President Recep Tayyip Erdoğan on Tuesday to encourage him to clear the way for Sweden and Finland to join.
The two leaders met Wednesday, and Biden praised Erdoğan for his support of NATO's enlargement. They also discussed ways to export Ukrainian grain to ease food shortages around the world.
"You're doing a great job, I just want to thank you," Biden said.
Not all of the conversations at the NATO summit involved European security.
Biden sat down Wednesday with South Korean President Yoon Suk Yeol and Japanese Prime Minister Fumio Kishida, who were attending the conference as the alliance looks to strengthen its ties in the Indo-Pacific region and address challenges from China.
The three leaders discussed North Korea's nuclear and ballistic missile programs, which Biden said the three found "deeply concerning."
Biden called "trilateral cooperation" essential and said the meeting was an opportunity for the leaders to coordinate a shared response, as U.S. officials say the isolated nation may soon conduct another nuclear test.
At the leaders dinner on Wednesday, Biden attended with two of his granddaughters, Finnegan and Maisy, instead of his wife, Jill. The U.S. president introduced them to his Turkish and Spanish counterparts.
Associated Press writers Aamer Madhani and Chris Megerian in Washington and Monika Scislowska in Warsaw, Poland, contributed to this report.