Will any NATO member invoke Article 4 or Article 5 before 1 January 2018?
Article 4 was invoked by Turkey in 2015 in response to developments in Syria and by Poland in 2014 in response to developments in Ukraine (Economist, NATO, Radio Free Europe/Radio Liberty). Article 5 has been invoked once, by the United States in response to a terrorist attack in 2001 (NATO).
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No NATO member invoked Article 4 or Article 5. This question was closed as "no" with an end date of 1 January 2018.