NATO celebrated 75 years of collective defense across Europe and North America on 4th April 2024. The alliance’s founding treaty was signed on April 4, 1949, in Washington.
- Collective defence means that an attack against one Ally is considered as an attack against all Allies.
- The principle of collective defence is enshrined in Article 5 of the North Atlantic Treaty (Washington Treaty).
- NATO invoked Article 5 for the first and only time in its history after the 9/11 terrorist attacks against the United States.
- NATO has taken collective defence measures on several occasions, including in response to the situation in Syria and the Russian invasion of Ukraine.
- NATO has standing forces on active duty that contribute to the Alliance’s collective defence efforts on a permanent basis.
