The order to dismiss Lt. Gen. Mykola Oleshchuk was published on the presidential website.

“We need to protect people. Protect personnel. Take care of all our soldiers,” Zelensky said in an address minutes after the order was published. He said Ukraine needs to strengthen its army on the command level.

U.S. experts have joined the Ukrainian investigation into the crash, the air force said.

Meanwhile, a Russian attack on the northeastern city of Kharkiv using powerful plane-launched glide bombs killed five people, including a 14-year-old girl on a playground, and wounded 47 others, regional Gov. Oleh Syniehubov said.

The bombs struck five locations across the city, which had a prewar population of around 1.4 million people, the governor said.

One of the bombs hit a 12-story apartment block, setting the building ablaze and trapping at least one person on an upper floor. Emergency crews searching for survivors feared the building could collapse.

Zelensky pointed to the Kharkiv strikes as further evidence that Western partners should scrap restrictions on what the Ukrainian military can target with donated weapons.

The Kharkiv strike “wouldn’t have happened if our defense forces had the capability to destroy Russian military aviation at its bases. We need strong decisions from our partners to stop this terror,” Zelensky said.

F-16s are one of the weapons that could be used to hit Russian bases behind the front line.

Oleshchuk said on Telegram that “a detailed analysis” was already being conducted into why the F-16 jet went down Monday, when Russia launched a major missile and drone barrage at Ukraine.

“We must carefully understand what happened, what the circumstances are, and whose responsibility it is,” Oleshchuk wrote in the post.

The crash was the first reported loss of an F-16 in Ukraine, where the warplanes arrived at the end of last month. At least six are believed to have been delivered by European countries.

Military analysts say the planes will not be a game-changer in the war, given Russia’s massive air force and sophisticated air defense systems. But Ukrainian officials welcomed the supersonic jets, which can carry modern weapons used by NATO countries, for offering an opportunity to hit back at Russia’s air superiority.

Elsewhere, the Russian army is making slow but gradual progress in its drive into eastern Ukraine, while Ukrainian forces are holding ground in the Kursk border region of western Russia after a recent incursion.