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 Russian drone shot down in the village of Wyryki-Wola, Poland, on Sept. 10, 2025. Wojtek Radwanski/AFP via Getty Images

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

“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,” Foreign Minister Lars Lokke Rasmussen told reporters.