KYIV — Ukrainian President Volodymyr Zelenskyy told his top commander, Gen. Valery Zaluzhny, that he was firing him in a meeting on Monday, according to a senior official familiar with the conversation — a disruptive military shake-up amid Ukraine’s struggles on the battlefield and after months of friction between the president and the popular general.

Zaluzhny remains in his post for now, but a formal presidential decree is expected to confirm his ousting nearly two years into Russia’s invasion and as Moscow’s forces appear to be gaining the strategic initiative on some parts of the front.

On Monday, Zelenskyy’s spokesman, Serhiy Nykyforov, denied that Zaluzhny had been fired. “There is no subject of conversation,” Nykyforov told reporters. “There is no order. The president did not dismiss the commander in chief.”

Nykyforov on Wednesday did not immediately reply to messages from The Washington Post seeking any updated comment.

It is far from clear that any new commander will be able to improve Ukraine’s difficult situation on the battlefield without significantly more forces and weapons — precisely what Zaluzhny has demanded of Zelenskyy, adding tension to what was already a fraying relationship.

Zaluzhny’s popularity — both within the military and among ordinary citizens — makes his removal a political gamble for Zelenskyy. It also poses strategic risks at a time when Russia has intensified its attacks and Western security assistance for Kyiv has slowed. The general has built strong rapport with his Western counterparts and has often been able to advocate directly for certain materiel and seek counsel on battlefield strategy.

It was unclear whether Zelenskyy and his team had planned for the dismissal to happen this week before details of Monday’s meeting leaked to some media and to channels on the Telegram social media app. But tension between the men had been building for months.

Last year’s highly anticipated Ukrainian counteroffensive, using soldiers trained by NATO allies and with Western weapons and equipment, reclaimed little territory, falling far short of expectations. Zaluzhny and his American counterparts disagreed sharply over tactics, and the Ukrainian commander ultimately ignored U.S. advice to concentrate his forces, which he believed could have caused far higher casualties.

In their conversation Monday, Zelenskyy told Zaluzhny that Ukrainians have grown tired of war and that the country’s international backers have also slowed military assistance, so perhaps a new commander would rejuvenate the situation, the person familiar with their conversation said.

Two individuals spoke about the meeting on the condition of anonymity to be candid about the highly sensitive situation with unpredictable implications for the war and Ukraine’s security. Senior members of Zaluzhny’s staff are also expected to be removed, one person said.

In Monday’s meeting, differences between the two boiled over because of disagreement about how many soldiers Ukraine needs to mobilize this year, according to the two people familiar with the exchange.

Zaluzhny proposed mobilizing close to 500,000 troops, a figure Zelenskyy viewed as impractical given the scarcity of uniforms, guns and training facilities and the potential challenges related to recruitment, the people said. Zelenskyy has also said publicly that Ukraine lacks the funds to pay so many new conscripts.

Zaluzhny countered that Ukraine is already short of forces because of mounting casualties and needs to match 400,000 new soldiers that Russia plans to mobilize, one person familiar with the conversation said.

Andrii, a deputy battalion commander, denounced Zaluzhny’s expected removal with an epithet. Andrii, like other soldiers, is being identified only by his first name because he was not authorized to speak publicly.

Zaluzhny “has sensible thoughts on mobilization,” Andrii said. “People are like, ‘We don’t need mobilization — everything is just fine there,’ but they’re not … here. They don’t know what’s happening here.”

It was not immediately clear who will replace the 50-year-old Zaluzhny.

One leading candidate is Ukraine’s head of military intelligence, 38-year-old Lt. Gen. Kyrylo Budanov. His appointment would potentially signal a move toward asymmetric tactics — such as the drone strikes deep into Russian territory that Budanov has often ordered - in a war where the front lines have seen little change in more than a year. But Budanov, with a background in special forces, does not have experience as an army commander.

Another option is Col. Gen. Oleksandr Syrsky, the 58-year-old commander of Ukraine’s ground forces, who was credited with leading the defense of Kyiv in the first month of the war and then orchestrating a successful counteroffensive in the northeastern Kharkiv region in fall 2022. But among rank-and-file soldiers, Syrsky is especially disliked, considered by many to be a Soviet-style commander who kept forces under fire too long in the eastern city of Bakhmut when Ukraine should have withdrawn.

Both Budanov and Syrsky are considered favorites of Zelenskyy and Andriy Yermak, the chief of the presidential office and Zelensky’s closest adviser. Nearer the front, however, there seems to be little appetite for change.

“My personal opinion is you can’t do something like this right now — Zaluzhny is someone 80 percent of the military considers a good authority,” said Oleksandr, a battalion commander fighting in eastern Ukraine.

“For what is he being removed? It’s not clear. And who will replace him? Syrsky? God, I hope not. No one in the army likes Syrsky,” Oleksandr added.

Zaluzhny was offered another post but declined, and he plans to retire from the military, according to the senior official. Reached by The Post, Zaluzhny declined to comment.

For now, he remains in the top job, and the formal order dismissing him could be delayed. Last year, the head of Zelenskyy’s faction in parliament announced that Oleksii Reznikov, then the defense minister, would be ousted, but Reznikov stayed in the post for months before being removed.

“This is a catastrophic step,” Oleksandr said. “When this becomes official, we’re screwed. The morale of both the military and society will go way down.”

Friction between Zelenskyy and Zaluzhny has been brewing for months, and the general has expected he could be dismissed since summer 2022, the person said.

Zaluzhny has been Ukraine’s commander in chief since Russia’s invasion in February 2022 and, according to opinion polls, rivals Zelenskyy in popularity, making him a potential political threat if a presidential election were to be held. Elections are currently barred in Ukraine because of martial law but under normal conditions should have taken place this year.

“There’s only one explanation: The Zelenskyy government is just putting his missteps … on Zaluzhny’s shoulders,” said a soldier fighting in the besieged eastern city of Avdiivka. “Zelenskyy is just very dependent on ratings, and he understands completely that Zaluzhny’s rating right now is much higher than his own. And that’s it. I think that politics shouldn’t interfere with the military doing their work.”

Though Ukrainian officials have privately hinted at distrust between Zaluzhny and Zelenskyy over the past year, the discord has spilled into open view in recent months. Last fall Zaluzhny referred to the war as a “stalemate” in an interview with the Economist magazine. Zelenskyy publicly rebuffed those remarks.

Another source of tension has been the gap between what Zaluzhny has requested for Ukraine’s military and what Kyiv’s political leaders have been able to draw from allies and partners, a second person familiar with the Monday meeting said. “He says in conversations with the minister of defense: ‘It’s not my job to get this; it’s your job,’” the person said.

Proposed aid for Ukraine has stalled in Washington and Brussels because of internal political disputes in the United States and the European Union. House Republicans have blocked a White House request for an additional $60 billion related to the war in Ukraine.

New Ukrainian military leadership is unlikely to change that, as the stalled security assistance has been tied to reaching a bipartisan deal for sweeping U.S. border policy changes.

“I don’t know who will be next, what kind of decisions were made, but maybe they just want to hear some good news from the head commander, like, ‘Everything is going dandy, it’s cool,’ but that’s not going to happen,” said Andrii, the deputy battalion commander.

Until now, Ukraine has enjoyed relative stability in its military ranks compared with its invading enemy. Russian President Vladimir Putin named Gen. Valery Gerasimov to the top job one year ago, dismissing Gen. Sergei Surovikin, who had been in the post for just three months.

“The Kyiv regime has many problems, and everything has gone wrong there, that’s for sure,” Kremlin spokesman Dmitry Peskov said Wednesday when asked about Zaluzhny’s possible dismissal. “Obviously, the failed counteroffensive and problems at the front increase the disagreements between members of the Kyiv regime,” Peskov added.

Hudson reported from Washington. Anastacia Galouchka and David L. Stern in Kyiv, Serhiy Morgunov in Warsaw and Natalia Abbakumova in Riga, Latvia, contributed to this report.