The statement came after an unidentified object was reported entering NATO airspace on Sunday morning, triggering alerts in Poland, Lithuania and neighbouring Latvia.
Lithuanian Defence Minister Robertas Kaunas said the object was believed to have travelled north from Poland.
He proposed a joint investigation with his Polish counterpart, as Poland’s military separately investigated a possible airspace violation.
Poland's military said on Sunday morning it was verifying a possible violation of its airspace by an unidentified object.
Polish airports in the eastern city of Lublin and in Rzeszów in the southeast resumed flight operations following a temporary closure in the morning to allow for military aviation actions, the Polish Air Navigation Services Agency said in a post on X.
Lithuania told residents in central and northern parts of the country to seek shelter for about an hour on Sunday morning after an unidentified flying object entered its airspace, the army and national crisis management centre said.
During the "red" alert, NATO air police fighters were scrambled to the area and Kaunas airport, near Lithuania's second-largest city, was temporarily closed, the crisis management centre also said.
The NATO aircraft were unable to visually identify the object due to cloudy weather and did not attempt to shoot it down, it added.
Ukrainian drones have repeatedly entered NATO airspace in the Baltic region in recent months. Kyiv has said they were steered off course by Russian signal jamming.
This has stoked concerns that Russia's war in Ukraine could spill across NATO's borders.
(mo/gs)
Source: PAP, Reuters