Within hours of officially joining the alliance this week, Swedish soldiers joined the other new NATO member, Finland, in the Nordic component of the largest NATO exercises since the Cold War ended.

Called Nordic Response, the exercises began Thursday in Finland and Norway and included 20,000 participants from 13 countries. Swedish Defense Minister Pal Jonson — in a post on the social media platform X, formerly Twitter — said Sweden contributed about 4,500 personnel.

Jonson said they joined Finnish and Norwegian personnel for three days of high-intensity war games in a subarctic climate. “It is important to be able to contribute this special Swedish-Norwegian-Finnish capability to NATO,” Jonson said in his post.

Speaking Saturday in Troms, Norway, alongside his counterparts from Finland, Antti Hakkanen, and Norway, Bjorn Arild Gram, Jonson said the Nordic units showed they can work together in a challenging environment. “Together, we make northern Europe more secure, and today’s northern flank of NATO is more complete.”

Nordic Response is part of NATO’s Steadfast Defender exercise series, which includes approximately 90,000 total personnel from NATO allied countries. The exercises began in January and continue until May, covering all parts of Europe.

Finland and Sweden applied for NATO membership in 2022, not long after Russia’s invasion of Ukraine. Both abandoned long-standing military neutrality that was a hallmark of the Nordic states’ Cold War foreign policy.

Finland’s membership was approved last year, but Sweden’s was held up by objections from members Turkey and Hungary and not finalized until this week. Both countries add significant militaries to the alliance.

Finland’s 1,336-kilometer (830-mile) border with Russia is now the longest among NATO allies.

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