In the 73 years since the North Atlantic Treaty Organization (Nato) was founded, member nations have activated article 4 of its founding treaty only half a dozen times. The latest instance was on February 24, the day Russia invaded Ukraine. Eight Nato members – Bulgaria, the Czech Republic, Estonia, Latvia, Lithuania, Poland, Romania and Slovakia – immediately invoked the article, thereby convening a consultation of Nato’s principal decision-making body, the North Atlantic Council.
Article 4 can be triggered when one or more Nato members deem the “territorial integrity, political independence or security” of any of the member states to be threatened. The North Atlantic Council meets regularly to discuss all items on its agenda, from military capability development to operations. When article 4 is triggered, however, the council prioritises the raised issue and discusses it instantly.
Although under article 4, member states do not have any other obligation than to consult, they usually agree on a joint decision or action. By contrast, article 5, which is about the collective defence of the member states specifically, stipulates that “an armed attack against one or more of” the allies “shall be considered an attack against them all”.
