From all of us at #NATO, we wish you a happy and peaceful New Year! #WeAreNATO pic.twitter.com/gcLgBnWA7S— NATO (@NATO) December 29, 2017
NATO - Topic: Collective defence - Article 5 Mar 22, 2017 - 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.
Article 5 is enacted again.