Finland and Sweden have formally requested membership in NATO, which the US supports

Signaling what they called a “new era,” leaders of Finland and Sweden said Sunday they will seek membership in the North Atlantic Treaty Organization within days, a move almost certain to escalate geopolitical tensions arising from the Russian war in Ukraine.

Having dealt several significant if limited setbacks to Moscow’s forces, Ukraine expressed renewed optimism over its conduct of the war and the wider ramifications — not the least of which is the likelihood of a larger NATO.

At a joint news conference in the presidential palace in Helsinki, President Sauli Niinisto and Prime Minister Sanna Marin announced the decision by Finland — which has long been a neutral country — to apply for entry into the U.S.-led alliance. The move would significantly alter the trans-Atlantic security architecture in existence since the end of World War II. “This is a historic day,” Niinisto said.

“A new era begins.” In Berlin on Sunday at a meeting of the foreign ministers of the 30 NATO member states, U.S. officials quickly welcomed Finland’s announcement. “I am very confident that we will reach consensus,” U.S. Secretary of State Antony J. Blinken said. $2 for 2 months Subscribe for unlimited access to our website, app, eEdition and more CLAIM OFFER He asserted in answer to reporters’ questions about opposition to NATO expansion from member Turkey, whose resistance is rooted in Scandinavian support for Kurdish separatists. “This is a process, and NATO is a place for dialogue,” Blinken said.

A short time later, the foreign minister of Sweden, Ann Linde, announced her country also would begin a formal application on Monday, after the ruling Social Democratic Party decided after more than a century to drop its policy of military neutrality.

“The Russian invasion of Ukraine has deteriorated the security situation for Sweden and Europe as a whole,” she said. Swedish Prime Minister Magdalena Andersson added: “It is not something against Russia, but is what we think is best for us,” acknowledging that a spate of retaliation including cyberattacks was possible.

Finland shares a more than 800-mile border with Russia, which views any expansion of NATO toward its territory as a grave security threat. Sweden sits on Finland’s western flank and is also partially bordered by the Baltic Sea. Ukraine’s emergence as a Western ally that could potentially join NATO is one of the major reasons Russian President Vladimir Putin has given for invading Ukraine.