A spiralling public row erupted among the top ranks of the military in Ukraine on Thursday, risking throwing uncertainty over the war effort at a time when Kyiv is in one of its strongest positions in months.

The split came after President Volodymyr Zelenskyy shook up his wartime government, including replacing his popular defense minister, who had been brought in six months ago, but clashed with the traditional military establishment.

Thousands poured into the streets across Ukraine to protest the ouster of Mykhailo Fedorov, who has been seen as an innovator of the country's successful drone technology.

The overhaul, which also included replacing his prime minister, could become a test of Zelenskyy's political authority as Ukraine's fight against Russia's full-scale invasion approaches four-and-a-half years. Zelenskyy has remained in office under martial law because wartime elections are prohibited, but has periodically reshuffled his government.

The moves threw Ukraine's military leadership into an unwelcome crisis at a time when its actions against Russia are starting to bear fruit and as Moscow has unleashed unrelenting aerial attacks.

Zelenskyy was forced to call for unity on Thursday to halt signs of an emerging split after Fedorov issued stunning public criticism of the army's top commander.

Following Fedorov's removal, Zelenskyy said he had asked Maj. Gen. Yevhen Khmara to perform the defense minister's duties in the meantime, according to a post on the Telegram messaging app.

Since January, Khmara has been acting head of the state's security service, known as the SBU. He had previously led the SBU's elite Alpha special forces unit.

"Khmara has gained extensive and, in many respects, unprecedented experience with technological combat operations," Zelenskyy said.

Kyiv's troops have largely halted the pace of Russia's advance while pounding Russian oil and military sites with long-range drones, triggering a nationwide fuel crisis inside its neighbor.

Plea for 'unity'

After being forced to resign, Fedorov on Thursday accused Gen. Oleksandr Syrskyi, the commander of Ukraine's armed forces, of dividing the country.

"Instead of figuring out how to defeat Russia asymmetrically – which is the commander-in-chief's task – he figured out how to split the country," Fedorov told reporters.

He criticized slow bureaucracy and a lack of flexibility, questioning whether Ukraine could defeat Russia with Syrskyi in charge of the army.

Fedorov said he was willing to work with Syrskyi, "but we encountered a situation in which all the initiatives we proposed began to be blocked."

"In this configuration, I personally don't know how to win the war," he said, wearing his trademark jeans and dark T-shirt, speaking in front of a large screen showing drones.

He also alleged Syrskyi had engineered his removal through an ultimatum issued to Zelenskyy after months of clashes.

Zelenskyy himself issued a plea for "unity" and said the two sides – the defense ministry and the army command – were barely on speaking terms.

"A president in wartime should not have to choose in such a situation, honestly," he said, speaking in Kyiv alongside U.K. Prime Minister Keir Starmer, who was making his final foreign visit before leaving office next week.

"I would very much like unity."

'New rules'

A soldier serving in Ukraine's army told Agence France-Presse (AFP) the political chaos in Kyiv could hit the war effort.

"For some, replacing a minister is merely a political reshuffle. For us, it can determine whether a needed drone arrives on time, whether essential equipment is purchased," they said, asking to speak anonymously to criticize the decision.

In a public statement, Syrskyi tried to stem the criticism, defending his results and calling to "focus on the war."

But one of his most senior commanders – a rumored possible successor – came to Fedorov's defense and called for the pace of reform to continue.

Joint Forces Commander Mykhailo Drapaty said the army "needs change" and "new rules" as he thanked Fedorov for "not being afraid to tackle issues."

Syrskyi, 60, initially organized the defense of Kyiv in February 2022, and seven months later masterminded a successful counteroffensive in the Kharkiv region. Born in 1965, he attended the Moscow Higher Military Command School before serving in the Soviet Artillery Corps before the USSR's collapse in 1991.

In Kyiv, over a thousand people gathered on a central square, singing Ukraine's national anthem, waving Ukrainian and European Union flags and chanting "shame" and "bring Fedorov back."

Analysts said Zelenskyy had backed his trusted army chief over an outsider defense minister at a key moment of the war.

The Ukrainian military has rallied under Fedorov, slowing Moscow's front-line advance to a virtual standstill and striking refineries and other energy sites inside Russian territory, causing widespread fuel shortages, Western officials and analysts say.

The deputy commander of Ukraine's air force, Pavlo Yelizarov, resigned in protest of Fedorov's ouster. And some lawmakers were trying to thwart his removal, refusing to hold a vote on a replacement for Fedorov.

Under Fedorov, Ukraine significantly increased soldiers' salaries and outlined plans to allow for phased demobilization, providing relief for soldiers fighting at the front.

Before becoming the defense minister in January, Fedorov headed Ukraine's digital transformation policies.

Local media reported protests in several other cities, including Lviv, Odesa and Dnipro.

Protests are relatively rare in wartime Ukraine, which has seen society rally behind the military and, mostly, Zelenskyy.

As the war has dragged on, however, major corruption allegations against Zelenskyy's inner circle and scandals in the military, particularly over recruitment and the treatment of conscripts, have triggered episodes of public outcry.

Meanwhile, the Ukrainian Parliament on Thursday overwhelmingly approved Serhii Koretskyi, the head of state energy company Naftogaz, as the country's new prime minister.

In nominating Koretskyi, Zelenskyy cited his record in the energy sector and argued he was best prepared to guide Ukraine through another winter, when Russian attacks on the power grid intensify.

Unlike other senior government officials, the 48-year-old engineer did not rise through political parties, parliament, or the civil service. He spent more than two decades managing fuel and food businesses before being picked to run some of Ukraine's most troubled state-owned energy companies and gained a reputation as an effective crisis manager who could make them profitable.