What is NATO Article 4?
Under NATO’s founding treaty, any member can unilaterally invoke Article 4. It allows allies to register their concerns but stops short of a formal request for assistance and does not oblige fellow members to take any action.
Instead, it triggers a consultation mechanism — giving members a chance to “exchange views and information, and discuss issues prior to reaching agreement and taking action.” This could pave the way for joint NATO action, but it does not necessitate it.
This would be the eighth time Article 4 has been invoked since NATO was established in 1949. In 2022, several Eastern European nations, including Poland, invoked it after Russia’s invasion of Ukraine. Poland also invoked Article 4 in March 2014, after Russia illegally annexed Ukraine’s Crimean Peninsula.
Poland’s decision to invoke Article 4 this time sets it apart from other recent airspace violations. Romania, another NATO member, has detected suspected Russian drones within its borders on multiple occasions and said it detected suspected fragments of a Russian drone in its territory, but it did not activate Article 4. On another occasion, in 2022, a projectile that NATO judged to be an errant Ukrainian air defense missile landed in Polish territory, killing two. Polish officials said the evidence suggested an unfortunate accident and said Russia was ultimately to blame for launching strikes that required Ukraine to defend itself.