Finland formally joined the North Atlantic Treaty Organization on Tuesday, more than doubling the length of the alliance's border with Russia and drawing a warning of "retaliatory measures" from Moscow. "Finland is stronger and safer within the alliance, and the alliance is stronger and safer with Finland as its ally," said Secretary of State Antony Blinken. Finland's President emphasized his country's desire to promote stability in Europe. Finland and Sweden began seeking expedited NATO membership – and the military support it can provide – within weeks of Russia's invasion of Ukraine last year. Sweden awaits approval. "The era of nonalignment in our history has come to an end – a new era begins,” Finland's president said. This year is the 74th anniversary of NATO and Finland is its 31st member. Ukraine President Volodymyr Zelenskyy tweeted congratulations to Finland on joining the "only effective security guarantee in the region amid Russian aggression."