Sweden officially joins NATO after delayed process, ending longstanding military neutrality

Sweden's arduous path to joining the NATO alliance came to a successful close Thursday, as the Swedish prime minister and foreign minister deposited the country's "instrument of accession" at the State Department in Washington.

In a lighthearted ceremony, U.S. Secretary of State Antony Blinken posed for photos with Swedish Prime Minister Ulf Kristersson, with the two holding a blue folder containing the document. Blinken quipped, "Well, good things come to those who wait."

"With receipt of this instrument of accession, let me be the very first to welcome Sweden as a party to the Washington Treaty and the 32nd member of the North Atlantic Treaty Organization," Blinken continued.

Blinken remarked on Sweden's longstanding military neutrality, and how the country was moved to end its tradition after Russian President Vladimir Putin invaded Ukraine in 2022. Sweden was called to defend democracy and recognized the existential threat Russia's aggression presented to European nations, he said.

"None of this was easy, none of this was obvious," Blinken said, adding it had taken "nearly two years of tireless diplomacy" to add Sweden to the alliance.

"Sweden is now a NATO member," Kristersson said on X earlier. "Thank you all Allies for welcoming us as the 32nd member. We will strive for unity, solidarity and burden-sharing, and will fully adhere to the Washington Treaty values: freedom, democracy, individual liberty and the rule of law. Stronger together."

Sweden's membership had been slowed by objections from Turkey and Hungary. The U.S. was able to eventually incentivize Turkey by approving the sale of fighter jets to the country, and Hungary signed off on Sweden's addition this week.

"This is a historic day," NATO Secretary General Jens Stoltenberg said in a statement. "Sweden will now take its rightful place at NATO's table, with an equal say in shaping NATO policies and decisions. After over 200 years of non-alignment Sweden now enjoys the protection granted under Article 5, the ultimate guarantee of Allies' freedom and security. Sweden brings with it capable armed forces and a first-class defense industry."

Sweden's flag will be raised alongside those of the other 31 Allies in a ceremony at NATO headquarters in Brussels on March 11 and simultaneously at NATO commands across Europe and North America, the alliance said.

-ABC News' Ellie Kaufman contributed to this story.