During a ceremony in Brussels, Finnish Foreign Minister Pekka Haavisto signed an accession document and handed it to US Secretary of State Antony Blinken, officially making Finland the 31st member of NATO.

NATO Secretary General Jens Stoltenberg remarked that Finland's NATO membership was "exactly the opposite" of what Russian President Vladimir Putin had as a proclaimed purpose of the invasion of Ukraine: "to get less NATO," according to The Guardian.

The NATO chief added that Finland and Sweden will shortly join the alliance as full members and noted that Finland's NATO membership "takes away the leeway for Russia to misjudge Nato's preparedness to safeguard Finland."

With Finland joining NATO, the alliance's border with Russia will be extended by almost 1,300 kilometers (830 miles). Before Tuesday, five NATO nations and Russia shared a boundary of around 1,215 kilometers (755 miles). NATO's land border with Russia more than doubles as a result of Finland's admission.

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Russia Blasts Finland's NATO Membership

On Monday, Russia threatened it would increase its military presence near Finland if NATO moved soldiers or hardware to the newest member country, per CNN.

Dmitry Peskov, a spokesman for the Kremlin, said that Russian officials would closely monitor what happens in Finland. He also said that the expansion of NATO via Finland's NATO membership violates Russia's "security and our national interests."

Finland and Sweden dropped years of military nonintervention to join NATO when the Russia-Ukraine war started, completing an expedited application procedure initiated in May.

Russia's attack on Ukraine prompted the two countries to seek the protection of Article 5 of the NATO charter, which states that an assault on one member is an attack on all.

That effectively implies that all NATO countries, including the US, would defend Finland if it were to come under invasion or assault, per the BBC.

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