Poland’s leader said a Russian missile may have struck Polish territory during a massive Russian attack on Ukraine overnight. If confirmed, it would mark the first time a Russian missile has hit Poland since the war began.

Russian missiles have briefly entered Polish airspace during previous strikes on western Ukraine, but a missile has never hit Poland itself. The incident raises immediate questions about NATO’s collective defense commitments, as Poland is a member of the alliance.

Officials in Warsaw are investigating the strike, which reportedly occurred near the Ukrainian border. The Polish government has convened an emergency meeting of its national security council to assess the situation and determine an appropriate response.

Russia has not commented on the allegation. The potential strike comes as Russia intensifies its aerial bombardment of Ukraine’s energy infrastructure ahead of winter, increasing the risk of spillover into neighboring NATO countries.