As Finland plans to join Nato, a look at how countries join the alliance

Nato's membership has increased from 12 to 30 countries through eight rounds of enlargement. The Republic of North Macedonia became the latest country to join Nato on March 27, 2020

On march 1, 2023, Finland's parliament approved legislation that paves the way for the country to join the North Atlantic Treaty Organization (Nato). Both Finland and Sweden abandoned decades of non-alignment in the region after Russia began its "special military operation" and invaded Ukrainian territory last year.

Nato was founded in 1949 with 12 original signatories. However, Nato's "Open door policy", based on Article 10 of its founding treaty, allows it to admit new members within its folds. Any decision to invite a country to the alliance is made on the basis of consensus among all allies. 

Nato's membership has