General · 17 January 2026
NATO Article 5 explained ?
Article 5 of NATO's founding treaty states that an armed attack against one member nation shall be considered an attack against all members. This collective defense provision requires each member to assist the attacked ally, but allows each country to determine what form of assistance is necessary. The assistance can include but does not require military force. Article 5 has been invoked only once in NATO's 75-year history following the September 11, 2001 terrorist attacks on the United States.
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