The Trump administration has once again threatened to take control of Greenland either by acquiring it or through the use of military force to “deter our adversaries in the Arctic region.”Greenland, which is a semi-autonomous territory of Denmark, already hosts the Pituffik Space Base, which the US operates in coordination with Danish authorities. Both the US and Denmark are founding members of NATO, the most powerful military alliance.European and Canadian leaders have jumped to support Denmark and Greenland, saying they are working on a plan in the event the United States follows through with its threats.Analysts have said that any attempt by the US to seize Greenland would be an unprecedented move in NATO’s history and raise serious questions about the survival of the alliance and the limits of Article 5, which was designed to defend against an external aggressor. What happens if one NATO member attacks another?Collective defence is NATO’s governing principle, where Article 5 of the North Atlantic Treaty states that an armed attack against one NATO member is considered an attack against all.This has been a binding pledge since 1949, when the alliance came together and one that has forged solidarity between North America and Europe.Because Article 5 requires unanimous agreement from all members to be invoked, a conflict between two members would lead to an impasse, as the alliance cannot vote to go to war against itself.The only time Article 5 has been invoked was following the September 11, 2001, attacks in the US. [Al Jazeera]In this timeline, Al Jazeera examines the closest instances when NATO members have faced potential conflict with each other. (Al Jazeera)Limi …
