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The North Atlantic Treaty, signed in Washington on 4 April 1949, gave birth to the Atlantic Alliance, which is strictly defensive and regional in nature (its geographical scope is limited to Europe and North America by Article 6 of the Treaty). Based on the Alliance, the organisation of the same name – the North Atlantic Treaty Organisation (NATO) – has developed over the following years, constituting an indispensable instrument of collective defence and military cooperation between its Member States, as well as a crucial forum for political and strategic dialogue between the two shores of the Atlantic.

The cornerstone of the Atlantic Alliance is the principle of collective defence, enshrined in Article 5 of the Washington Treaty, by virtue of which: “The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognised by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area”.

The Alliance’s deep entrenchment in the UN system is reaffirmed by the second paragraph of Article 5, which states that “Any such armed attack and all measures taken as a result thereof shall immediately be reported to the Security Council. Such measures shall be terminated when the Security Council has taken the measures necessary to restore and maintain international peace and security.

To date, the only case when Article 5 was invoked by the North Atlantic Council (NAC) was after the terrorist attack on the Twin Towers in New York, which took place on 11 September 2001. This is indicative of the transformations that have affected the international scene since the end of the Cold War, in response to which the Alliance has undertaken a profound adaptation process that is still ongoing, which meets the need to interpret and face the strategic scenarios of the contemporary world.

The most recent outcomes of this continuous adaptation process are incorporated in the “Strategic Concept”, which is the Alliance’s central strategic vision document, renewed approximately every ten years. Its most recent version is the Madrid Strategic Concept, adopted at the 2022 Summit, which identifies NATO’s three main functions (core tasks): deterrence and defence, crisis prevention and management, and cooperative security.


The sole decision-making body of NATO is the North Atlantic Council (NAC), which meets at the level of Member States’ Permanent Representatives, or at the level of Ministers (meetings of Foreign and Defence Ministers are organised regularly), or of Heads of State and Government, as most recently happened in the case of the Madrid Summit on 28-30 June 2022. NAC meetings are chaired by the Organisation’s Secretary General, a position held since 1 October 2014 by Norwegian Jens Stoltenberg.

The subsidiary body of NAC is the Military Committee, formed by the Member States’ Chiefs of Defence or their Military Representatives. It assists the North Atlantic Council and implements – in the military sphere – the decisions taken at the political level by the latter.

NATO’s command structure comprises two Strategic Commands, namely the Allied Command Operations (ACO) and the Allied Command Transformation (ACT).

The former is responsible for planning and carrying out NATO’s operations. Its headquarters, namely the Supreme Headquarters Allied Powers Europe (SHAPE) – are located in Mons (Belgium) and are led by the Supreme Allied Commander in Europe (SACEUR), a position held since 1 July 2022 by US General Christopher Cavoli.

ACT, instead, is located in Norfolk (USA) and is responsible for ensuring continuous adaptation and enhancing the Alliance’s operational readiness.

An adaptation of the NATO Command Structure (NCS) was adopted in 2018. This now also includes a Cyberspace Operations Centre in Mons (Belgium) and a third Joint Force Command, in Norkfolk, designed to protect transatlantic lines of communication, as well as a Joint Support and Enabling Command in Ulm (Germany) to facilitate the fast movement of troops and equipment across Europe.


Member States

NATO currently consists of 31 Member States. Italy is one of the 12 founding Members, along with Belgium, Canada, Denmark, France, Iceland, Luxembourg, the Netherlands, Norway, Portugal, Great Britain and the United States. The following countries later joined the Alliance:

1952: Greece and Turkey;

1955: Germany;

1982: Spain;

1999: Czech Republic, Hungary and Poland;

2004: Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia;

2009: Albania and Croatia;

2017: Montenegro;

2020: North Macedonia;

2023: Finland.