What is Article 5 of NATO’s Founding Treaty? (Excerpts from NATO and the Scourge of Terrorism - 9/11 Aftermath)
On 12 September 2001, NATO decided that, “if it is determined that the attack against the United States was directed from abroad, it shall be regarded as an action covered by Article 5 of the Washington Treaty”.
This was the first time in the Alliance's history that Article 5 was invoked.
Article 5 of the Washington Treaty
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.
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.
NATO's Strategic Concept recognizes the risks to the Alliance posed by terrorism.
What Does Article 5 Mean?
Article 5 is at the basis of a fundamental principle of the North Atlantic Treaty Organization. It provides that if a NATO Ally is the victim of an armed attack, each and every other member of the Alliance will consider this act of violence as an armed attack against all members and will take the actions it deems necessary to assist the Ally attacked.
This is the principle of collective defense.
Article 5 and the Case of the Terrorist Attacks Against the United States
The United States has been the object of brutal terrorist attacks (9/11). It immediately consulted with the other members of the Alliance. The Alliance determined that the US had been the object of an armed attack. The Alliance therefore agreed that if it was determined that this attack was directed from abroad, it would be regarded as covered by Article 5. NATO Secretary General, Lord Robertson, subsequently informed the Secretary-General of the United Nations of the Alliance's decision.
Article 5 has thus been invoked, but no determination has yet been made whether the attack against the United States was directed from abroad. If such a determination is made, each Ally will then consider what assistance it should provide. In practice, there will be consultations among the Allies. Any collective action by NATO will be decided by the North Atlantic Council. The United States can also carry out independent actions, consistent with its rights and obligations under the UN Charter.