Polish and allied aircraft were activated early Wednesday to safeguard NATO-member Poland’s airspace after Russia launched an air attack on Ukraine’s western regions that border Poland, according to the Polish military.

“Polish and allied aircraft are operating in our airspace, while ground-based air defence and radar reconnaissance systems have been brought to the highest state of readiness,” operational command of the Polish armed forces said in a post to X.

“These actions are preventative in nature and are aimed at securing the airspace and protecting citizens, especially in the area adjacent to the threatened region,” it added.

Polish authorities have closed Warsaw International Airport, CNN reported.