(Bloomberg) -- Finland completed a shift in power on Friday after Alexander Stubb was sworn in as the 13th president of the Nordic country, giving him oversight of foreign policy and national security. 

Stubb, a 55-year-old former prime minister, formally took over from Sauli Niinisto as head of state in an inauguration ceremony in parliament, pledging to the best of his ability promote the wellbeing of the people of Finland.

He represents continuity in foreign and security policy in the role that’s focused on safeguarding independence and peace next to a belligerent Russia.

“We are now facing a new era,” Stubb said in his inauguration speech in the Finnish parliament. “The things that were supposed to bring us together — interdependence, trade, technology, energy, information, and currency — are now tearing us apart. The instruments of cooperation have been weaponized.”

A key task during Stubb’s six-year term will be to help steer Finland’s integration into the North Atlantic Treaty Organization, which it joined in April in response to Russia’s full-scale invasion of Ukraine. He has said Finland wants to be an “active” member in the defense alliance as it seeks to keep neighboring Russia at bay.

Read More: Finland’s Next President Pledges to Take Active Role in NATO

Finland’s closest neighbor, Sweden, is in the final stages of accession into NATO with formal entry expected next week or shortly thereafter. The bloc’s northern enlargement will strengthen the defense of the eastern flank, allowing the alliance to dominate the Baltic Sea region and facilitating the transit of troops and equipment from Norway’s North Sea ports to the east.

Read More: Sweden Clears Final Hurdle to Join NATO With Hungary Vote

Finland guards 1,300 kilometers (800 miles) of border with Russia, the frontier that is now closed to curb the flow of Russian-assisted asylum seekers, seen by Finns as a deliberate attempt to undermine their national security. Finland is also investigating the rupture of an undersea gas pipeline after a Hong Kong-flagged ship dragged its anchor on the seabed, damaging the interconnector.

In addition to his role as the country’s top diplomat, the president is also the supreme commander of Finland’s defense forces. The country of 5.5 million — roughly the size of Minnesota — has more artillery than France and Germany combined and can call on as many as 280,000 troops in time of war. The president shares oversight of foreign relations with the government, but domestically he has limited powers.

Niinisto, 75, reached a constitutional limit after serving two terms.

Stubb — a Swedish-speaking Finn who communicates fluently in a number of languages and has published 16 books — has held all the top ministerial posts in Finland, including the finance and foreign affairs portfolios. Most recently the director of the Florence School of Transnational Governance at European University Institute in Italy, Stubb has a PhD in international relations.

He is also an avid athlete, having completed numerous marathons and triathlons, and as a teenager, he also played ice hockey and golf, which took him to study at Furman University in South Carolina.

Stubb said his main duty as president will be to ensure that Finns can live in peace.

“However, if push comes to shove, I am ready to make difficult decisions to ensure the security of our country,” he said. “We must remain alert.”

--With assistance from Thomas Hall.

(Updates with Stubb’s comments throughout)

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