Timeline of NATO [trans-Atlantic alliance] expansion since 1949

Finland and Sweden are nearing decisions on whether to ditch their long-standing policy of military nonalignment and join NATO in the wake of Russia's invasion of Ukraine. They would become the 31st and 32nd members of the trans-Atlantic alliance, which was founded by the U.S. and 11 other countries following World War II. Here's a timeline showing key developments in NATO's history. 1949: The North Atlantic Treaty Organization is founded to deter Soviet expansion and a revival of European militarism. The 12 original members are the United States, Canada, Britain, Belgium, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway and Portugal. 1952: Greece and Turkey join in the alliance's first expansion. 1955: West Germany joins NATO. In response, the Soviet Union and seven countries in Eastern Europe form the eight-nation Warsaw Pact. 1982: Spain becomes the 16th member of NATO. 1991: The Soviet Union collapses and the Warsaw Pact is dissolved. 1994: Finland and Sweden join NATO's Partnership for Peace program. The following year they join the European Union, effectively ceasing to be neutral, but remaining military nonaligned. 1999: Three former Warsaw Pact nations — the Czech Republic, Hungary and Poland — join NATO. 2001: Article 5 in the NATO treaty, which stipulates that an attack on any NATO member is an attack on all, is triggered for the first time after the 9/11 attacks on the United States. 2002: The NATO-Russia Council is formed to help NATO members and Russia to work together on security issues. 2003: NATO takes command of the International Security Assistance Force in Afghanistan (ISAF). 2004: The biggest NATO expansion to date as seven countries become members: Bulgaria, Romania, Slovakia, Slovenia, Estonia, Latvia and Lithuania. The latter three are the only former Soviet republics to have joined the alliance. 2008: NATO countries welcome Ukraine and Georgia's aspirations to join the alliance, angering Russia. In August, Russia wins a short war with Georgia over the breakaway regions of South Ossetia and Abkhazia, which Moscow recognizes as independent states. 2009: Croatia and Albania become NATO members. 2011: NATO enforces a no-fly zone over Libya. Sweden takes part with fighter jets on reconnaissance missions. 2014: NATO suspends most cooperation with Russia after its annexation of Crimea. 2015: NATO ends the ISAF mission in Afghanistan. The alliance remains in Afghanistan to train local security forces until the Taliban takeover in 2021. 2017: Montenegro joins NATO. 2020: North Macedonia becomes NATO's 30th member. 2022: Sweden and Finland explore the possibility of NATO membership after Russia's invasion of Ukraine.