when was article 5 invoked

NATO’s Article 5 has been formally invoked only once: in response to the 11 September 2001 terrorist attacks on the United States.

Quick Scoop

• Article 5 is the collective defence clause in the North Atlantic Treaty: an attack on one ally is treated as an attack on all.

• It was politically agreed and “invoked” on 12 September 2001, the day after the 9/11 attacks, when NATO members declared that if the attacks were directed from abroad, they would fall under Article 5.

• After the United States briefed allies on the investigation, NATO confirmed on 2 October 2001 that the 9/11 attacks were indeed covered by Article 5, making this the first and so far only time Article 5 has been activated.

In practical terms, when people ask “when was Article 5 invoked,” they are referring to this post‑9/11 decision in September–October 2001 in support of the United States.

Information gathered from public forums or data available on the internet and portrayed here.