What Is the North Atlantic Treaty Organization (NATO)?

The North Atlantic Treaty Organization (NATO) is an alliance of 32 member states from North America and Europe, created in 1949, with the goal of safeguarding the freedom and security of members through political and military means.

NATO first strives to prevent conflict through diplomatic channels as part of the organization’s effort to promote democratic values and enable member states to solve problems peacefully. When diplomatic efforts fall short, NATO’s military might may be activated to engage in crisis management under the principle of collective defense, which states that “an attack against one is an attack against all.”

Understanding the North Atlantic Treaty Organization (NATO)

The NATO alliance includes countries in both Europe and North America, which creates an important transcontinental link that allows member nations to cooperate when it comes to defense and security. Member states also consult and work together when a multinational crisis develops involving nonmembers.

The North Atlantic Treaty Organization was created on April 4, 1949, with the signing of the North Atlantic Treaty as an attempt to deter Soviet expansionism, prevent nationalist militarism in Europe, and encourage European political integration.

The treaty contains just 14 articles and begins with a preamble that says in part: “The Parties to this Treaty reaffirm their faith in the purposes and principles of the Charter of the United Nations and their desire to live in peace with all peoples and all governments...”

A summary of the articles of the North Atlantic Treaty appears below:

• Article 1: Members agree to the use of peaceful means to settle disputes.
• Article 2: Members will attempt to eliminate conflict and encourage economic collaboration.
• Article 3: Members will maintain their individual capacity to resist armed attack.
• Article 4: Members will consult each other when the territorial integrity, independence, or security of any member is threatened.
• Article 5: Members agree that an armed attack on any party is an attack on them all, with each member taking action it deems necessary, including the use of armed force.
• Article 6: An armed attack on any member is defined as an attack on the territory, forces, vessels, or aircraft of any member.
• Article 7: This treaty does not alter any obligation of members of the United Nations (U.N.).
• Article 8: This treaty does not conflict with agreements currently in force between members or a third state.
• Article 9: Members will establish a council whereby they can discuss matters concerning the treaty.
• Article 10: With unanimous agreement, members may invite any other European state to join the treaty.
• Article 11: Ratification of the treaty will follow each party’s respective constitutional process.
• Article 12: After 10 years, members may convene to review the treaty, if any of them so requests.
• Article 13: After 20 years, any member may cease to be a member one year after giving notice.
• Article 14: The English and French versions of the treaty are equally authentic and shall be deposited in the archives of the government of the United States.
  

The treaty on which NATO is based states that “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” may apply for membership in the organization. Through NATO’s Membership Action Plan, aspiring members can prepare for membership and “meet key requirements by providing practical advice and targeted assistance.”

NATO’s Current Membership

Currently, 32 countries are members of NATO. Member states, along with the year they joined the organization, appear below:

• Albania (2009)
• Belgium (1949)
• Bulgaria (2004)
• Canada (1949)
• Croatia (2009)
• Czech Republic (1999)
• Denmark (1949)
• Estonia (2004)
• Finland (2023)
• France (1949)
• Germany (1955)
• Greece (1952)
• Hungary (1999)
• Iceland (1949)
• Italy (1949)
• Latvia (2004)
• Lithuania (2004)
• Luxembourg (1949)
• Montenegro (2017)
• Netherlands (1949)
• North Macedonia (2020)
• Norway (1949)
• Poland (1999)
• Portugal (1949)
• Romania (2004)
• Slovakia (2004)
• Slovenia (2004)
• Spain (1982)
• Sweden (2024)
• Turkey (1952)
• United Kingdom (1949)
• United States (1949)

NATO Operations, 1949 to Present Day

NATO’s two-part mission to preserve freedom and security is achieved through political and military means. By promoting democratic values while enabling member states to cooperate on mutual defense and security, NATO’s first approach to conflict always focuses on a peaceful resolution.

When diplomacy fails, the organization’s military might, triggered by Article 5, comes into play. This can be accomplished by NATO alone or in cooperation with other nations and international organizations.

When NATO was established, its primary role was to act as a deterrent to military aggression. To that end, throughout the Cold War, NATO forces were not involved in a single military engagement. With the end of the Cold War in the early 1990s, the organization saw the emergence of new threats that required an increasingly proactive role, including its first post-Cold War crisis response operation in the Balkans in 1992. Multiple NATO operations in the Balkans ended with the signing of the Dayton Peace Accord in 1995, with the organization’s peace support mission ending in 2004.

On Oct. 4, 2001, after it had been determined that the 9/11 terrorist attacks in New York and Washington, D.C., had come from abroad, NATO agreed on a package of eight measures to support the United States, including the International Security Assistance Force (ISAF), which it led from August 2003 to December 2014. The ISAF was succeeded on Jan. 1, 2015, by the Resolute Support Mission (more on that below).

NATO airlifted close to 3,500 tons of needed supplies to Pakistan and deployed engineers, medical units, and specialist equipment to assist in relief operations after the devastating earthquake there in October 2005. Then, following the uprising against the Gadhafi regime in Benghazi, Libya, in February 2011, the U.N. Security Council adopted Resolutions 1970 and 1973 in support of the Libyan people, introducing a no-fly zone enforced by NATO. NATO conducted a support operation in Iraq from 2004 to 2011 that consisted of training, mentoring, and assisting the Iraqi Security Forces. The Resolute Support Mission (RSM) in Afghanistan was launched in 2015, following the completion of the mission of the ISAF. This mission was terminated in September 2021. NATO has been involved in boosting its air policing missions since Russia’s first invasion of Ukraine and annexation of Crimea in 2014. This includes patrolling Allied airspace including over Albania, Montenegro, Slovenia, the Benelux countries, and the Baltic region. Additional current operations include supporting the African Union, conducting training missions in Iraq, securing the Mediterranean Sea, and carrying out operations in Kosovo.

Most recently, NATO is helping to coordinate Ukraine’s requests for assistance following Russia’s second invasion in 2022 and is supporting members in the delivery of humanitarian and non-lethal aid. Individual NATO members are also sending weapons, ammunition, and medical supplies as well as financial assistance.

2010 Strategic Concept

In November 2010, NATO member heads of state and government adopted the “Strategic Concept for the Defense and Security of the Members of the North Atlantic Treaty Organization” at the NATO Summit in Lisbon, Portugal.

The purpose of the agreement was to clarify the role NATO would play in the “next phase in NATO’s evolution,” specifically to:

• Reconfirm the bond between nations to defend one another against attack
• Commit NATO to preventing crises, managing conflicts, and stabilizing post-conflict situations
• Offer global partners more political engagement with NATO and a substantial role in shaping NATO-led operations
• Commit NATO to the goal of creating the conditions for a world without nuclear weapons
• Restate a commitment to keep the door to NATO open to all European democracies that meet the standards of membership
• Commit NATO to continuous reform toward a more effective, efficient, and flexible alliance
  

The Bottom Line

The North Atlantic Treaty Organization (NATO) was organized in 1949 primarily as a response to postwar Soviet aggression and nationalist militarism in Europe and to encourage European political integration. In response to NATO, the Soviet Union created the Warsaw Pact in 1955. (The Warsaw Pact disbanded in 1991.)

NATO’s goals include peace through diplomacy and security through military action if necessary. Article 5 of the North Atlantic Treaty states that “an armed attack against one or more [member states] in Europe or North America shall be considered an attack against them all.” As a consensus-based alliance, decisions by NATO must be unanimous.

NATO has a long history of involvement in worldwide conflict, including both diplomacy and military action. The organization’s effectiveness has most recently been tested by Russian aggression in Ukraine.