North Macedonia has officially become the 30th member of NATO.
The country's flag will be raised alongside those of the other 29 member nations at NATO headquarters in Brussels and two other commands simultaneously on Monday.
“North Macedonia is now part of the NATO family, a family of 30 nations and almost one billion people," NATO Secretary General Jens Stoltenberg said in a statement.
"A family based on the certainty that, no matter what challenges we face, we are all stronger and safer together."
Joining NATO and the European Union (EU) marks the end of a long quest for the former Yugoslav republic, as a dispute with neighbouring Greece over the country's name stalled progress for more than two decades.
North Macedonia was previously known as Macedonia, a name it shared with a Greek province.
Under a 2017 deal with Athens, the country changed its name and Greece agreed to drop objections to its NATO and eventual EU membership.
It has been a big week for North Macedonia - on Thursday, EU leaders gave the Balkans country the green light to begin EU membership talks.
North Macedonian President Stevo Pendarovski said: "This is a historic success that, after three decades of independence, finally confirms Macedonian security and guarantees our future."
Cover image: Library picture of the NATO flag and troops (Picture: PA).