Ukrainian President Volodymyr Zelenskyy dismissed Mykhailo Fedorov as the country’s minister of defense after just six months in office as part of a major shake-up in Kyiv’s leadership.

The move, which has been the subject of speculation, was confirmed when Fedorov published a farewell social media post on Wednesday.

It followed Prime Minister Yulia Svyrydenko’s resignation at the request of the president on Tuesday, which triggered the removal of and subsequent need to reappoint all the ministers currently serving in her cabinet.

“It has been a great honor to serve the Ukrainian people as Minister of Defense,” Fedorov wrote in the post. “Thank you to everyone who defends Ukraine and works for victory.”

Fedorov’s departure surprised many Ukrainians, who credited him with helping Ukraine secure recent victories.

Under his tenure, Fedorov secured dozens of drone deals with international partners and instituted military structure and budget reforms.

Supporters of Federov, including adviser Serhii Sternenko, argued the change could slow ongoing military efforts.

In his farewell message, Fedorov listed 22 accomplishments he said his team completed during his tenure, including restricting Russian access to Starlink, instituting draft and military pay reform, and launching the country’s antiballistics initiatives.

The outgoing minister also listed three goals he said remained unfinished, including transforming the ministry’s structure to NATO standards and “common sense,” completing the transition of procurements to tenders, and building a “culture of accountability for decisions.”

Sternenko, also said in a post on Wednesday that he was leaving his position at the Ministry of Defense.

“From now on, I am no longer an advisor to the Minister of Defense,” he wrote, “which undoubtedly reduces the opportunities to qualitatively help change the situation in the military with drones.”

Zelenskyy has not publicly explained the decision or named a successor.

The Economist reported that Fedorov, a 35-year-old with a tech background, was rumored to be in conflict with multiple factions within Ukraine’s military administration.

Others saw his initiatives as too progressive, according to Kyiv-based political analyst Volodymyr Fesenko in comments to Kyiv Independent.

“There is alleged friction in Fedorov’s relationship with [Commander-in-Chief Oleksandr] Syrskyi,” Fesenko said. “Not everyone is happy with Fedorov’s proposals for reforming the military, particularly his plans to overhaul the way the Defense Ministry operates.”

Ukraine’s Interior Minister, Ihor Klymenko, has reportedly been offered the job to replace Fedorov, according to the Kyiv Independent, which cited anonymous sources.

Despite leaving the ministry, Fedorov vowed to keep serving the country in other ways.