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Fact Sheet: A NATO primer

Washington, July 27 — As NATO’s purpose and value continues to be debated throughout the U.S. election campaign, Center for a New American Security (CNAS) Strategy and Statecraft Program and CNAS Strategy and Statecraft Program Researcher Adam Twardowski have written a primer answering key questions about the alliance, including what the alliance requires of members and whether it is up to dealing with modern threats.

The full primer is below:

The question of U.S. commitments to partners and allies has been a focal point of this year’s U.S. presidential election cycle. The Washington Treaty, which forms the basis of the North Atlantic Treaty Organization or NATO, has attracted the most attention. As candidates from both sides debate the pros and cons of membership and examine burden sharing, CNAS experts have written a primer on the Alliance, defense spending by its members, and U.S. commitments to NATO.

1. What does NATO membership require members to do?

NATO is charged with ensuring the security of its member states through political and military means. To join NATO, aspiring countries must meet political, economic, and military goals that will enable them to contribute effectively to the operation of the Alliance. These goals include instituting stable democratic governance, market-based economic systems, and the rule of law. The key military obligation of NATO member states is collective self-defense. Article 3 of the 1949 Washington Treaty specifically stipulates that “in order more effectively to achieve the objectives of this Treaty, the Parties, separately and jointly, by means of continuous and effective self-help and mutual aid, will maintain and develop their individual and collective capacity to resist armed attack.”

2. Are members obliged to spend two percent of gross domestic product (GDP) on defense?

No. The 1949 Washington Treaty does not obligate members to spend a certain percentage of their GDP on defense. During the 2002 Prague Summit, Alliance leaders set two percent of GDP as a standard for national defense spending. This was not a binding treaty obligation, however, but rather a benchmark goal, and one that has proven to be elusive. Political pressure and consultation are currently the only means available to inch member states closer to the goal of two percent defense spending.

3. How many members are spending that much?

Between the 2002 Prague Summit and the 2014 Wales Summit, defense spending among NATO members generally trended downward, and today only five member states, the United States, the United Kingdom, Poland, Greece, and Estonia, actually spend two percent of their GDP on defense. At the Wales Summit, members pledged to turn the trend around and put a halt to further defense cuts. Today, 22 of the 28 member states spend a larger portion of their economy on national defense relative to 2015, leading to Alliance-wide growth of 2.65 percent. More can be done, but progress has been made on strengthening burden sharing.

4. What is Article 5?

Article 5 is the clause in the original 1949 Washington Treaty upon which the Alliance’s commitment to collective defense is built. Simply put, it states that an attack against one NATO ally will be considered an attack against them all. Article 5 states that the Alliance “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.” The phrase “such action it deems necessary” within Article 5 is important in that it means that each state individually decides how, or if, to come to the aid of another. The invocation of Article 5 does not obligate any specific course of action, nor does it require a collective Alliance-wide response. The only required action the Treaty spells out is that after a decision has been taken to use armed force in defense of a member state that decision must be reported to the U.N. Security Council and that the armed force “shall be terminated when the Security Council has taken the measures necessary to restore and maintain international peace and security.”

5. Has Article 5 ever been invoked?

For the majority of its history, the West assumed that Western European states would invoke Article 5 in the face of potential Soviet aggression. However, the only time Article 5 has ever been invoked was in the defense of the United States following the 9/11 attacks. NATO forces played a key role in post-9/11 counterterrorism operations outside the Euro-Atlantic area. As a result of the 9/11 attacks, NATO launched its first ever anti-terror operation, Eagle Assist, followed by Active Endeavor, in which NATO’s Standing Naval Forces deployed to patrol the Eastern Mediterranean.

6. Is an Alliance created in 1949 capable of addressing today’s security threats?

The fall of the Berlin Wall led to probing questions regarding NATO’s purpose and character in the new century. Recognizing the need to “go out of area or out of business,” NATO decided early on to adopt proactive measures addressing a range of new security threats. During the Balkan Wars, for instance, NATO took an active role in addressing the military and humanitarian calamity unfolding on the European continent by bombing Serbian military positions and later deploying a peacekeeping force that enforced the region’s fragile ceasefire. After 9/11, it took on wider counterterrorism and counterpiracy missions and committed personnel and resources to Afghanistan to conduct security operations and build up local Afghan security forces. Today, it is focused on developing new tools in the cyber, energy, and hybrid domains, as well as enhancing partnerships around the world. Even as it pursues all these initiatives, Russia’s resurgence in eastern Europe has magnified the need for the Alliance to return to its traditional deterrence posture. The most recent summit in Warsaw provided a much-needed opportunity to showcase NATO’s revitalized commitment to deterrence and resilience through significantly higher defense spending, new battalions in nervous eastern member states, and continued expansion of membership opportunities and partnerships.

NATO’s post-Cold War evolution shows it is an Alliance capable of adaptation and innovation. Could it do more? Of course. It operates by consensus so change happens at an incremental pace, but it has adjusted to the changing face of international security and made meaningful contributions.

7. Does the United States need NATO?

The United States has a unique ability to project power globally and is the most capable member of the Alliance in terms of military forces. But partners and allies provide a number of benefits without which the United States could not easily project its power or ensure its security-international legitimacy, interoperable forces, command and control, new tools, and different types of partnerships. In return, the United States provides leadership and capabilities that many allies lack, as well as unmatched influence in shaping policy and steering Alliance-wide priorities. The United States needs NATO more than ever because it has a strong geostrategic and economic interest in a unified and peaceful Europe, which is now threatened by aggressive Russian maneuvers on NATO’s eastern flank. Key NATO allies like Turkey are instrumental in U.S.-led efforts to disrupt and destroy ISIS. In a time of unprecedented security and economic challenges to the international order, the endurance of alliances like NATO provides much needed stability and certainty in a rapidly shifting security environment.

Smith is available for interviews. To arrange an interview, please contact Neal Urwitz at or 202-457-9409

The Center for a New American Security (CNAS) is an independent and nonpartisan research institution that develops strong, pragmatic and principled national security and defense policies.

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