NATO Allies Have Been Discussing Invoking Article 4: What to Know

Article 4 has been activated nine times since 1949—most recently, after members reported incursions by Russian air units into their airspace.

Police and army inspect damage to a house destroyed by debris from a shot down Russian drone in the village of Wyryki-Wola, eastern Poland, on Sept. 10, 2025. Polish Prime Minister Donald Tusk said a violation of Polish airspace a major provocation aimed at the EU and NATO member. Wojtek Radwanski/AFP via Getty Images

Denmark on Sept. 26 confirmed there are no plans to invoke NATO’s Article 4, after drone incursions in its airspace earlier this week.

Foreign Minister Lars Lokke Rasmussen told reporters, “Article 4 has been activated nine times in NATO’s entire history, and twice recently in relation to Poland and Estonia, so we have no reason to do so.”