Joining NATO

Bulgaria was admitted to NATO in 2004. Reaching that point, however, involved a long process lasting 14 years.

On 18 March 2004, the National Assembly of the Republic of Bulgaria ratified the North Atlantic Treaty, which NATO's founding countries had first signed in Washington on 4 April 1949. This day is marked as Bulgaria's official accession to the North Atlantic Treaty Organization.
On 29 March 2004, the instruments of accession to the North Atlantic Treaty of the seven new countries—Bulgaria, Estonia, Latvia, Lithuania, Slovakia, Slovenia and Romania—were deposited in Washington. Consequently, 29 March 2004 is recognised as the official date of Bulgaria's accession to the North Atlantic Alliance.