The principle of collective defence is at the very heart of NATO’s founding treaty. It remains a unique and enduring principle that binds its members together, committing them to protect each other and setting a spirit of solidarity within the Alliance.
Highlights
- 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 Washington Treaty.
- NATO invoked Article 5 for the first time in its history after the 9/11 terrorist attacks against the United States.
- NATO has taken collective defence measures on several occasions, for instance in response to the situation in Syria and in the wake of the Russia-Ukraine crisis.
- NATO has standing forces on active duty that contribute to the Alliance’s collective defence efforts on a permanent basis.