US President Joe Biden celebrated Finland's historic induction into Nato on Tuesday, praising it as “the fastest ratification process” in the military alliance's modern history.
Finland's accession is viewed in the West as a victory over Russian President Vladimir Putin and his war in Ukraine.
“When Putin launched his brutal war of aggression against the people of Ukraine, he thought he could divide Europe and Nato. He was wrong,” Mr Biden said in a statement.
“Today, we are more united than ever.
“And together — strengthened by our newest ally Finland — we will continue to preserve transatlantic security, defend every inch of Nato territory, and meet any and all challenges we face.”
Finland officially joined the world’s biggest security alliance on Tuesday after completing a series of choreographed formalities at the alliance's headquarters in Brussels.
Finnish Foreign Minister Pekka Haavisto gave his country's Nato accession papers to US Secretary of State Antony Blinken, the keeper of the alliance's founding treaty.
The Nordic country's membership doubles Russia’s border with Nato.
Finland becomes Nato's 31st member
Moscow described Finland's inclusion as an “assault” on Russian security.
“The Kremlin believes that this is the latest aggravation of the situation,” Kremlin spokesman Dmitry Peskov told reporters. “The expansion of Nato is an assault on our security and Russia's national interests.”
Both Finland and Sweden launched their bid to join Nato months after Moscow's invasion of Ukraine, which shook the European continent's post-Second World War sense of security.
Helsinki overcame its last hurdle to joining the bloc when Turkey approved its membership bid last Thursday after months of negotiations.
US ambassador to Nato Julianne Smith on Monday expressed hopes that Sweden would join the alliance before its next meeting in July. Stockholm is still in talks with both Turkey and Hungary over its bid.
“I look forward to welcoming Sweden as a Nato member as soon as possible, and encourage Turkiye and Hungary to conclude their ratification processes without delay,” Mr Biden added in the statement.
