The North Atlantic Treaty was signed in 1949. However, Article 5 was neither triggered in 1961 when the Portuguese Colonial War started in Angola, nor after the Gulf of Tonkin Incident (1964) that started the (overt) U.S. involvement in the Vietnam War.

Portugal, as a founding member nation of NATO, could have activated Article 5 for U.S. and U.K. engagement in the war, and perhaps they could have kept their African colonies till today. Instead, the long lasting war triggered the April 1974 coup d'état in mainland Portugal, led to the collapse of the Estado Novo (the 2nd Republic) and its African colonial empire.

The U.S. was attacked by North Vietnam, and Portugal suffered from Cuba's intervention in Angola. Both NATO members were attacked by sovereign nations. Why, in these circumstances, was not only Article 5 not triggered, but also NATO as a military alliance did nothing to help?


1 Answer 1


Article 5 explicitly applies only to attacks taking place in Europe or North America. See http://www.nato.int/cps/en/natolive/official_texts_17120.htm?selectedLocale=en.

  • 4
    @gerrit: Article 6 expands the geographical scope or Article 5. Besides, what would you do if you attacked the Asian part of Turkey and NATO responded? Take NATO to court?!
    – MSalters
    Commented Apr 3, 2017 at 14:03
  • 3
    @MSalters Nope, I just wonder if some member states could use this to weasel their way out if Erdoǧan (already not very popular) invoked Article 5 claiming some Kurdish attack in Anatolia is an attack on Turkey and that all of NATO should now join forces to "liberate Turkey from Kurdish terrorists" or however Erdoǧan may choose to formulate it.
    – gerrit
    Commented Apr 3, 2017 at 14:07
  • 2
    @gerrit: In such cases, "such measures as deemed necessary" may be limited to a stern vote of disapproval in the UN. More realistically, NATO would classify it as a domestic issue. More importantly, even if NATO could avoid invoking Article 5 on geographical reasons, it still would limit future actions. By using incidental/ad-hoc reasons, NATO does not restrict itself.
    – MSalters
    Commented Apr 3, 2017 at 14:15
  • 2
    The question about Turkey and the NATO is already answered here.
    – Philipp
    Commented Apr 3, 2017 at 15:38
  • 3
    @MSalters Also, the North Atlantic Treaty doesn't say members can't intervene for attacks in other locations. A NATO member who's attacked anywhere can still request help from other members, and this help would fall under Article 51 collective self-defense.
    – cpast
    Commented Apr 3, 2017 at 16:31

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