WARSAW, Poland (AP) — Poland’s armed forces said Friday an unknown airborne object entered the country’s airspace from the direction of Ukraine and subsequently vanished off radars.

The Operational Command of the Armed Forces said on social media platform X, formerly Twitter, that the unidentified airborne object was observed by radars of Poland’s air defense system from the moment it crossed the border until the signal disappeared.

It said troops have been mobilized to identify and find the object.

Prime Minister Donald Tusk convened a meeting with the defense minister, military commanders and heads of national security bodies, to be followed by a meeting of the National Security Bureau.

There were no immediate reports of any explosion or casualties.

The governor of Lublin province in eastern Poland, Krzysztof Komorski, told the Onet news portal that the unidentified object appeared on radars near the town of Hrubieszow, where a border crossing with Ukraine is located. Komorski said he had no information to indicate the object landed in Lublin province.

Poland’s border with Ukraine is also the European Union and NATO border with Ukraine.