The dismissal was announced just a day after the Ukrainian military reported that an F-16 jet crashed and its pilot died while repelling a major Russian strike on Monday.

“I have decided to replace the commander of the Air Force of the Armed Forces of Ukraine. I am extremely grateful to all our military pilots, engineers, soldiers of mobile firing groups, and air defense units,” said Zelenskyy.

“We need to do the same at the command level - we need to become stronger. And we have to take care of people. To take care of the personnel. To take care of all our soldiers.”

He did not give a reason for the dismissal.

Ukraine’s General Staff said that General Lieutenant Anatoliy Kryvonozhka would temporarily perform the duties of commander.

F-16 down

The Ukrainian military did not provide an explanation for the crash on Monday but stated that the aircraft went down as it was nearing a Russian target. Oleshchuk said that U.S. partners were assisting in the investigation.

Oleshchuk also said that the reasons for the disaster would be thoroughly investigated and would not be kept secret from the public.

“The entire top leadership [of the state] immediately received the report on the disaster. We also received a preliminary report from our American partners, who have already joined the investigation,” he wrote on social media.

A U.S. defense official told Reuters that the crash did not appear to be the result of Russian fire, and possible causes from pilot error to mechanical failure were still being investigated.

The arrival of the first F-16 jets was a milestone for Ukraine in the fight against the full-scale invasion Russia launched over 2 years ago.