Finland and Sweden have officially applied for membership in the NATO military alliance, spurred by Russia's invasion of Ukraine.
NATO Secretary-General Jens Stoltenberg made the announcement Wednesday at the alliance's headquarters in Brussels, flanked by the ambassadors from both countries after receiving their formal application letters.
"This is a good day at a critical moment for our security," Stoltenberg said. "All allies agree on the importance of NATO enlargement. We all agree that we must stand together. And we all agree that this is an historic moment which we must seize."
Finland's parliament overwhelmingly voted to join NATO earlier Wednesday before Stoltenberg's announcement by a vote of 188-to-8.
The applications of Finland and Sweden mark a historic departure from their decades-long neutrality posture dating back to the Cold War. But Moscow's decision to invade neighboring Ukraine on February 24 raised fears in both countries, especially in Finland, which shares a long border with Russia.
All 30 NATO member nations are expected to quickly consider the applications, a process that normally takes up to a year.
But Turkish President Recep Tayyip Erdogan has expressed reservations about the Baltic neighbors joining the alliance, accusing them of giving safe haven to "terrorists" and imposing sanctions on Turkey.
Russian President Vladimir Putin warned the West that Moscow would respond if NATO bolstered its military presence in Finland and Sweden after the two Nordic countries declared Sunday they want to join the U.S.-dominated Western military alliance.
U.S. President Joe Biden will offer his personal support when he meets Thursday at the White House with Swedish Prime Minister Magdalena Andersson and President Sauli Niinistö of Finland.