Finland is set to join NATO on Tuesday, days after Turkey ratified the Nordic country's membership and set it on track to become the 31st member of the world's biggest military alliance.

All NATO members must vote unanimously to admit a new country into the alliance.

"This is an historic week," NATO Secretary-General Jens Stoltenberg told reporters in Brussels Monday, on the eve of a meeting of the alliance's foreign ministers. The move, he said, will make "Finland safer and our alliance stronger."

The addition of Finland, which shares a 1,340 kilometre (832 mile) border with Russia, will more than double the size of NATO's border with Russia.

Only a few technical steps procedures remain before Finland can join NATO's ranks:

ACCEPTANCE LETTERS

Turkey will on Tuesday hand its acceptance letter for Finland's accession to U.S. Secretary of State Antony Blinken at NATO headquarters in Brussels. The United States is the depositary, or safekeeper, of NATO under the alliance's 1949 founding treaty.

SIGNATURES

Stoltenberg will then invite Finland to present Blinken with its own acceptance document, signed by Foreign Minister Pekka Haavisto. Finnish President Sauli Niinistö authorized Haavisto to sign the document.

FULL MEMBERSHIP

Once Finland's membership acceptance document is handed over, the country will officially become a NATO member. A flag raising ceremony will be held at 1330 GMT (1530 CET) in Brussels on Tuesday.

FINLAND-SWEDEN

Finland and neighbouring Sweden jointly applied for NATO membership in May 2022. The countries, which have close cultural, economic and political ties, planned to enter the alliance simultaneously.

Sweden's bid, however, has stalled due to opposition from Turkey, whose president has said his country won't ratify membership before its disputes with Stockholm are resolved. The Turkish government has accused Sweden of being too soft on groups that it deems to be terror organizations.

Hungary's parliament also has yet to ratify Sweden's accession to NATO, and it remains unclear when it will do so. Stoltenberg said Monday that he hopes Sweden will join in coming months, before U.S. President Joe Biden and his NATO counterparts meet in Lithuania in July.

- AP