What is NATO?

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1 Member countries

NATO members

The most important players in the North Atlantic Treaty Organization are the member countries themselves.

There are currently 28 members

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  • Albania (2009)
  • Belgium (1949)
  • Bulgaria (2004)
  • Canada (1949)
  • Croatia (2009)
  • Czech Republic (1999)
  • Denmark (1949)
  • Estonia (2004)
  • France (1949)
  • Germany (1955)
  • Greece (1952)
  • Hungary (1999)
  • Iceland (1949)
  • Italy (1949)
  • Latvia (2004)
  • Lithuania (2004)
  • Luxembourg (1949)
  • Netherlands (1949)
  • Norway (1949)
  • Poland (1999)
  • Portugal (1949)
  • Romania (2004)
  • Slovakia (2004)
  • Slovenia (2004)
  • Spain (1982)
  • Turkey (1952)
  • The United Kingdom (1949)
  • The United States (1949)

NATO enlargement

NATO membership is open to “any other European state in a position to further the principles of this Treaty and to contribute to the security of the North Atlantic area.”

NATO also has what it calls the Membership Action Plan, which offers aspiring members practical advice and targeted assistance. In turn, aspiring members are expected to meet certain key requirements.

Illustration of a NATO meeting

2 Basic points

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2.1 A political and military Alliance

NATO’s essential purpose is to safeguard the freedom and security of its members through political and military means.

POLITICAL - NATO promotes democratic values and encourages consultation and cooperation on defence and security issues to build trust and, in the long run, prevent conflict.

MILITARY - NATO is committed to the peaceful resolution of disputes. If diplomatic efforts fail, it has the military capacity needed to undertake crisis-management operations. These are carried out under Article 5 of the Washington Treaty - NATO’s founding treaty - or under a United Nations mandate, alone or in cooperation with other countries and international organizations.

2.2 Collective defence

NATO is committed to the principle that an attack against one or several members is considered as an attack against all. This is the principle of collective defence, which is enshrined in Article 5 of the Washington Treaty.

So far, Article 5 has been invoked once - in response to the 9/11 terrorist attacks in the United States.

2.3 The Transatlantic link

NATO is an alliance of countries from Europe and North America. It provides a unique link between these two continents for consultation and cooperation in the field of defence and security, and the conduct of multinational crisis-management operations.

2.4 The 2010 strategic concept

Strategic Concepts lay down the Alliance’s core tasks and principles, its values, the evolving security environment and the Alliance’s strategic objectives for the next decade. The 2010 Strategic Concept defines NATO’s cores tasks as: collective defence, crisis-management and cooperative security.


3 Activities

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3.1 Decisions and consultations

NATO provides a unique opportunity for member countries to consult and take decisions on security issues at all levels and in a variety of fields.

A “NATO decision” is the expression of the collective will of all 28 member countries since all decisions are taken by consensus.

Each day, hundreds of civilian and military experts and officials come to NATO Headquarters to exchange information, share ideas and help prepare decisions when needed, in cooperation with national delegations and the staff at NATO Headquarters.

3.2 Operations and missions

  • Afghanistan   Kosovo
  • Securing the Mediterranean
  • Supporting the African Union

NATO takes an active role in a broad range of crisis-management operations and missions, including civil emergency operations.

NATO’s crisis-management operations are carried out under Article 5 of the Washington Treaty or under a United Nations mandate.

3.3 Partnerships

Over 40 non-member countries work with NATO on a wide range of political and security-related issues. These countries pursue dialogue and practical cooperation with the Alliance and many contribute to NATO-led operations and missions. NATO is also cooperating with a wide network of international organisations.

Partner countries do not have the same decision-making authority as member countries.

 Learn more
about NATO's partnerships

3.4 Developing the means to respond to threats

NATO has been engaged in continuous transformation for many years to ensure it has the policies, capabilities and structures required to deal with current and future threats, including the collective defence of its members.


4 Key events



Fall of the Berlin Wall


NATO develops partnerships with former adversaries after the break-up of
the Soviet Union


NATO engages in its first major crisis-management operation in
Bosnia and Herzegovina


Large-scale terrorist attacks in New York and Washington D.C.

NATO invokes Article 5 for the first time ever and adopts a broader approach to security


NATO takes command of the International Security Assistance Force - ISAF - in Afghanistan


NATO adopts the 2010 Strategic Concept "Active Engagement, Modern Defence"

 Go to NATO Declassified

5 Working structures

Member countries

Military Committee

International Military Staff

Allied Command Operations

Integrated Military Command Structure

View organigram