BRUSSELS — Finland formally joined the North Atlantic Treaty Organization on Tuesday, becoming its 31st member on the same day as NATO’s 74th anniversary.

The country applied to join NATO last May in a foreign policy U-turn prompted by Russia’s full-scale invasion of Ukraine. Finland’s entry brings to the alliance a new 1,340-kilometer border with Russia — as well as its own significant military capabilities.

Finland and Sweden initially planned to join the alliance together. But Turkey and Hungary dragged out the ratification process for the two countries, ultimately signing off on Finland’s bid last week but leaving Sweden hanging in the wind. 

On Tuesday this week, Turkey and Finland completed the final steps in the process, handing over accession documents to U.S. Secretary of State Antony Blinken. 

Standing alongside NATO Secretary-General Jens Stoltenberg and Finnish Foreign Minister Pekka Haavisto at NATO headquarters in Brussels, Blinken declared: “With receipt of this instrument of accession, we can now declare that Finland is the 31st member of the North Atlantic Treaty.”

The Finnish flag was then raised outside NATO headquarters. 

“The era of military nonalignment in our history has come to an end,” Finnish President Sauli Niinistö said at the accession ceremony, which was attended by senior officials and the alliance’s foreign ministers. “A new era begins,” he continued. 

“Finland’s membership,” the president emphasized, “is not targeted against anyone.” 

But Niinistö also underscored the importance of Sweden soon joining the alliance. 

“Finland’s membership is not complete without that of Sweden. Our persistent efforts for a rapid Swedish membership will continue,” the Finnish leader said. 

In his speech, Stoltenberg also made a nod to Stockholm’s ongoing accession bid. 

“This has been the fastest accession process in NATO’s modern history,” he said at the ceremony. “I look forward to welcoming Sweden into the alliance as soon as possible.”