Finland President Sauli Niinisto in a ceremony on Thursday signed legislation making his country part of the North Atlantic Treaty Organisation (NATO).
Finland last year sought to join the military alliance in response to Russia's war in Ukraine, and legislation incorporating NATO's founding treaties was passed in parliament in Helsinki on March 1.
Hungary and Turkey, the only NATO members that have yet to ratify Finland's membership, have both signaled that they will soon do so.
(Reporting by Essi Lehto; Editing by Mark Porter)