The North Atlantic Treaty Organisation is marking its 75th anniversary with a summit in Washington DC where it will welcome its newest member and assess global threats and defence priorities.
Nato was founded early in the Cold War to deter Soviet Union expansion and to prevent the rise of nationalist militarism in Europe.
Twelve founding nations launched Nato in 1949 and its ranks have now swelled to 32 countries (30 from Europe and two from North America). A number of nations, including Ukraine, hope to become members and this year Sweden is attending its first summit as a member.
Nato was a key pillar of western defence throughout the Cold War and has members bordering Russia, including original signatory Norway. Three former Soviet republics – Latvia, Lithuania and Estonia – are now part of the club. Finland joined last year and Sweden is the newest joiner after acceding to alliance membership in March.
Which countries are Nato members?
Nato was born out of the Second World War and many of its founding members reflect the alliance that, with help from the Soviet Union, brought down Nazi Germany.
France, the UK, Italy, Norway and Denmark were among the first European members. The US and Canada, both founding members, are still the only members not in Europe.
During the Cold War, Nato welcomed new members, including West Germany, Spain, Turkey and Greece.
After the Iron Curtain fell a number of eastern European nations joined Nato in 1999, including Poland and Hungary.
Three former Soviet republics – Latvia, Lithuania and Estonia – have since joined.
Nato also has dialogue with global partners in Asia-Pacific and the Middle East, including Japan, South Korea, Australia, New Zealand and the countries of the Istanbul Co-operation Initiative, as well as dialogue with the GCC.
What are the threats?
The military alliance has never been larger but is also facing potentially existential threats from outside and within. The challenges facing Nato include Russia’s war in Nato-aspirant Ukraine, an increasingly China, North Korea and Iran.
Nato also has a geopolitical interest in the Israel-Hamas war in Gaza.
France and Hungary are facing a rise in far-right populism and Nato host President Joe Biden is fighting a fierce election campaign against Donald Trump who has expressed doubts over Nato’s relevance. Nato also faces new threats as the effects of climate change mix with conflicts, extremism and terrorism.
While Russia poses an immediate challenge, China may pose more long-term and global challenges.
Who are the leaders to watch?
At 81, Joe Biden's age has become an issue in the US presidential election and his personal performance will be watched as much as policies and politics.
Ukraine’s Volodymyr Zelenskyy is expected to demand support to help fight Russia push for a quicker path to entering Nato membership.
Keir Starmer, who will be on his first transatlantic trip since becoming Prime Minister, has pledged to carry on the previous administration’s support of Ukraine.
French President Emmanuel Macron has just seen off a far-right election challenge but the vote ended with the French parliament having no majority.
Hungary’s Viktor Orban is a critic of Western military aid to Ukraine and has a warm relationship with Russia and China.
