The Swedish flag was raised for the first time over NATO headquarters in Brussels Monday ahead of the formal ceremony welcoming the Nordic country as the 32nd member of the alliance.

At a news conference immediately after, Swedish Prime Minister Ulf Kristersson joined NATO Secretary General Jens Stoltenberg in touting a stronger, more unified NATO.

“The security situation in our region has not been this serious since the Second World War, and Russia will stay a threat to Euro-Atlantic security for a foreseeable future,” Kristersson said. “It was in this light Sweden applied to join the NATO defense alliance to gain security, but also to provide security.”

Russia’s invasion of Ukraine in 2022 prompted both Sweden and Finland to seek membership in NATO after years in which both countries maintained military neutrality. Stoltenberg said, once again, that Russian President Vladimir Putin’s goals when he began the invasion have backfired.

“He wanted less NATO and more control over his neighbors. He wanted to destroy Ukraine as a sovereign state, but he failed,” Stoltenberg said. “NATO is bigger and stronger. Ukraine is closer to NATO membership than ever before.”

Sweden was formally welcomed into NATO last Thursday by U.S. Secretary of State Antony Blinken. About 20,000 Swedish military personnel participated in NATO exercises alongside Finnish and Norwegian troops last week in Norway and Finland.

After months of delay, Turkey ratified Sweden’s admission earlier this year, and Hungary did so in recent days.

Turkey had expressed concern that Sweden was harboring and not taking enough action against Kurdish groups that it regards as terrorists, and Hungary’s populist President Viktor Orban has shown pro-Russian sentiment.

Some information for this report was provided by The Associated Press, Reuters and Agence France-Presse.