This week, leaders from NATO member states and global partners met for a key summit in Lithuania.
Security concerns, war in Ukraine and potential new members have all been topics of interest, while Ukraine’s prime minister Volodymyr Zelenskyy has criticised delays around his country’s bid to join NATO.
But what does the alliance actually do, who is part of it, and how complicated is it to join?
Here’s what you need to know.
What is NATO?
NATO – the North Atlantic Treaty Organisation – is a security alliance created in 1949 in the aftermath of World War Two.
Its purpose was to secure peace in Europe, to promote cooperation among its members and to guard their freedom.
NATO guarantees the freedom and security of its members through political and military means.
Article 5 of the treaty reads “an armed attack against one … shall be considered an attack against them all”.
Who is in NATO?
The NATO alliance consists of 31 member states from North America and Europe.
These countries are called NATO allies, and come together to discuss political and security issues and make collective decisions by consensus.
The alliance first consisted of 12 countries: Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom and the United States.
Greece and Türkiye joined in 1952, followed by Germany in 1955.
Spain became a member in 1982, while the Czech Republic, Hungary and Poland joined in 1999.
Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia all became members in 2004, followed by Croatia and Albania in 2009.
Montenegro joined in 2017, North Macedonia joined in 2020, and Finland joined in 2023.
What does NATO do?
NATO’s primary purpose is to safeguard the freedom and security of all its members through political and military means.
The alliance also has partnerships with other organisations and countries and aims to contribute to peace and stability through crisis prevention and management.
NATO provides a forum for members to consult on issues and take decisions on political and military matters affecting their security.
All NATO decisions are made by consensus, meaning that all member countries have reached an agreement after discussion and consultation.
Which countries are trying to join NATO?
The process of joining NATO can take some time.
At the 2008 NATO summit in Bucharest, Romania, the allies agreed that Georgia and Ukraine will become members of NATO in future.
Sweden and Finland both applied to join in 2022 and while Finland is now a member, Sweden’s accession is not yet complete.
Sweden and Finland applied for NATO membership in 2022. Source: AP / Johanna Geron
NATO says its “door remains open” to any European country in a position to undertake the commitments and obligations of membership and contribute to security.
Countries that have declared an interest in joining the alliance are initially invited to engage in an intensified dialogue with NATO, and may then be invited to start what is called a Membership Action Plan (MAP).
Why isn’t Ukraine a member of NATO?
Ukraine has been pushing for entry to NATO since even before Russia started its invasion in February 2022.
NATO members have agreed Ukraine cannot join during the war, but have disagreed over how quickly it could happen afterwards and under what conditions.
Members in Eastern Europe have backed Ukraine’s stance, arguing bringing the country under NATO’s collective security umbrella is the best way to deter Russia from attacking again.
Countries such as the US and Germany have been more cautious, wary of any move they fear could draw NATO into a direct conflict with Russia.
Members have not specified the conditions Ukraine needs to meet or given a timeline for membership.
NATO has dropped the requirement for Ukraine to fulfil a MAP, effectively removing a hurdle to Ukraine’s way into the alliance.
Is Australia in NATO?
Australia is not a member of NATO, but cooperates with the alliance in areas of mutual interest as a partner across the globe.
Australia has worked with the alliance since 2005 and has been an “enhanced opportunities partner” since 2014.
Prime Minister Anthony Albanese is attending the NATO summit in Lithuania this week to observe and provide leaders with an Indo-Pacific perspective on global security.
He is also attending meetings with a number of world leaders, including his UK counterpart Rishi Sunak, Portuguese leader António Costa and Danish Prime Minister Mette Frederiksen.