Ukrainian President Volodymyr Zelenskyy announced late Sunday that he will replace the country’s defense minister, even as Kyiv’s counteroffensive appears to be gaining ground with its troops pushing into Russian-held territory.

The departure of Oleksiy Reznikov as defense chief marks the highest-level turnover in Zelenskyy’s inner circle since the start of the war in February 2022. It comes as the Ukrainian government is stepping up efforts to deal aggressively with corruption allegations involving military officials.

In a video message Sunday night, the Ukrainian leader announced that Reznikov would be replaced as defense minister by Rustem Umerov, the head of the country’s State Property Fund.

“Reznikov has gone through more than 550 days of full-scale war,” Zelenskyy said. “I believe the ministry now needs new approaches and other formats of interaction with both the military and society as a whole.”

There have been rumblings for weeks that Rezniko’s days were numbered. His reputation took several hits earlier this year over a handful of wartime scandals in the Defense Ministry in which officials were accused of profiteering. While Reznikov was never implicated, the revelations were a black eye not only for his ministry, but for him personally.

Zelenskyy called on the country’s parliament to approve the decision as soon as possible.

Reznikov has been one of the most prominent faces of Ukraine’s military leadership since Russia’s invasion, and has traveled throughout Europe to attend NATO meetings and to make his pitch to partners for more weapons, and to deliver aid pledges more quickly.

Having a seat at the table for NATO discussions over the past 18 months has brought him in close touch with defense chiefs across the NATO alliance, particularly with U.S. Defense Secretary Lloyd Austin. The two regularly speak by phone and huddle in person at monthly Ukraine Defense Contact Group meetings where a coalition of 50 countries decide what new weaponry to send to Kyiv.

The next meeting of the group will likely come in mid-September, and depending on how quickly the Ukrainian parliament moves, it could be the first time Umerov takes part in the high-level meeting with defense ministers.

Reznikov was scheduled to fly to the U.S. early this month for a meeting with Austin at the Pentagon, followed by sit-downs with the heads of the biggest American defense contractors to discuss new equipment purchases and deliveries, according to a person familiar with the planning.

Zelenskyy’s decision comes as Ukraine’s counteroffensive finally appears to making headway after weeks of slow progress.

U.S. National Security Council spokesman John Kirby said on Friday that Washington has seen signs that the counteroffensive is picking up pace. According to Kirby, officials have “noted over the last 72 hours or so some notable progress by Ukrainian armed forces,” particularly along the southern front in the region around Zaporizhzhia.

A top Ukrainian general said on Saturday that Kyiv’s forces had breached Russia’s first defensive line near Zaporizhzhia. Ukrainian troops were consolidating their hold on territory reclaimed in recent fighting and faster gains were expected as they pressed the weaker second line of defense, Brig. Gen. Oleksandr Tarnavskiy told the Guardian in an interview.