Sweden Officially Enters NATO Alliance, a Strategic Blow to Moscow

Sweden formally joined NATO on Thursday, becoming its 32nd member, two years after Russia’s invasion of Ukraine forced both Sweden and Finland to dump their traditional military nonalignment and seek the collective security of the American-led alliance.

After months of uncertainty caused by the hesitations of Turkey and Hungary, Sweden officially joined by depositing its legal paperwork — its instrument of accession to the North Atlantic Treaty — with the U.S. State Department in Washington.

In a brief ceremony in Washington, Secretary of State Antony J. Blinken received the documents from Ulf Kristersson, the Swedish prime minister, and said: “Good things come to those who wait.” Mr. Blinken said that “everything changed” after Russia’s invasion. “Swedes realized something very profound: that if Putin was willing to try to erase one neighbor from the map, then he might well not stop there.”

Mr. Blinken said Sweden’s membership is a clear example “of the strategic debacle that Ukraine has become for Russia,” adding: “Everything that Putin sought to prevent, he has actually precipitated by his actions, by his aggression.”

Mr. Kristersson said that “today is a truly historic day.” Sweden, he said, “will defend freedom together with the countries closest to us — both in terms of geography, culture and values.” He pledged that Sweden, which had largely dismantled its ground forces after 1989 but has maintained a powerful air force and navy, would soon reach NATO’s goal of spending 2 percent of G.D.P. on the military.

NATO is planning a ceremony on Monday to raise the Swedish flag at its Brussels headquarters, as well as at NATO commands across Europe and North America.

Jens Stoltenberg, the NATO secretary general, called it “a historic day.” In a statement, he said that “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 nonalignment Sweden now enjoys the protection granted under Article 5, the ultimate guarantee of allies’ freedom and security.”

Sweden, he continued, “makes NATO stronger, Sweden safer and the whole alliance more secure.”

The Russian government has said that it will now take undefined measures to enhance its own defense against the newly enlarged NATO, which has, with Sweden and Finland, a much longer land border with Russia than before.