Ukrainian Foreign Minister Dmytro Kuleba resigned on Wednesday, following the resignation of several other cabinet members in a sweeping reorganization of the Ukrainian government, the largest since the large-scale Russian invasion more than two years ago.

The upheaval comes at a crucial time in the war. Ukrainian troops seized part of Russia’s Kursk region in a surprise cross-border offensive last month, and Moscow continues to attack energy facilities across Ukraine, causing frequent power outages and fears of a harsh winter.

At least 51 people were killed on Tuesday in a Russian attack on the central Ukrainian city of Poltava.

“The fall will be extremely important for Ukraine. And our state institutions must be set up so that Ukraine achieves all the results we need,” Ukrainian President Volodymyr Zelensky said in a speech Tuesday night. “To do this, we need to strengthen a number of areas in the government — and personnel decisions are prepared.”

Zelensky is expected to travel to the United States this month to attend the United Nations General Assembly and has said he plans to present US President Joe Biden and presidential candidates Donald Trump and Kamala Harris with a “victory plan” to win the war.

Ukrainian lawmakers said they expect another round of resignations and dismissals, rumored for some time as part of a major government shakeup, to take place on Thursday. David Arakhamia, the leader of Zelensky’s Servant of the People party in the Ukrainian parliament said in a Telegram message that as much as 50 percent of the cabinet of ministers could be reshuffled.

At a meeting with his party in the Ukrainian parliament on Wednesday, Zelensky said the reshuffle was aimed at re-energizing the government and increasing efficiency in certain areas, according to Oleksandr Merezhko, the chairman of the parliament’s Foreign Affairs Committee.

Rumors of a reshuffle have been circulating in Ukraine for months. Nearly a quarter of cabinet posts are filled by caretaker ministers after previous resignations, said Andrii Osadchuk, a member of the Ukrainian parliament from the opposition Holos party.

Ukrainian analysts found it difficult to explain the logic of the reshuffle, noting that some of the people who resigned are expected to remain in high-ranking government positions.

“I don’t think anyone can explain why most of the changes are happening,” said Andrii Borovyk, the executive director of Transparency International Ukraine. “We can’t say that this is a new team in the government,” he added, noting that many of the new appointments currently serve as deputy ministers or as officials in the presidential office.

Since the large-scale Russian invasion in February 2022, Ukraine has been under martial law, and elections, normally held every five years, have been postponed indefinitely.

But since much of Ukraine’s foreign policy was already led by Zelensky and Andriy Yermak, the head of the presidential office, former US officials and experts saw the moves as a reshuffling of chairs in Ukraine’s cabinet rather than a full-scale personnel overhaul.

“These are decisions that Ukraine has to make and indeed the decision that the president has to make,” said former ambassador William Taylor, who led the U.S. embassy in Kiev in an acting capacity until January 2020. “I don’t expect this to be a problem in relations with the United States.”

Over the past year, Zelensky has taken a more robust approach with personnel changes. In September 2023, he replaced then-Defense Minister Oleksii Reznikov with Rustem Umerov and followed that up by replacing popular Gen. Valeriy Zaluzhnyi as commander-in-chief of the Ukrainian Armed Forces with Gen. Oleksandr Syrskyi in February. With the new moves likely to keep power in the hands of Zelensky and Yermak, some lawmakers were irritated by the changes.

“President Zelensky doesn’t believe in institutions, he believes in people,” said a Ukrainian lawmaker who spoke on condition of anonymity to discuss the ongoing changes. “But institutions need to work, and institutions need to have a strategy. That’s not how it works in Ukraine.”

In the wake of Kuleba’s resignation, Andrii Sybiha will be nominated as Ukraine’s foreign minister, two people familiar with the decision said. Sybiha was Yermak’s deputy in the presidential office until earlier this year and previously served as Ukraine’s ambassador to Turkey.

“He’ll have a different style than Kuleba,” Taylor said. “He’ll probably bring a bit more discipline to the (State Department). He’ll be more formal.”

As part of the changes, Deputy Prime Minister for European Integration Olha Stefanishnya’s portfolio is expected to be transferred to the Justice Ministry. Stefanishnya is expected to lead the ministry in an expanded role as the country negotiates accession to the European Union, said Alyona Getmanchuk, director of the New Europe Center, a Kyiv-based think tank.

Oleksandr Kamyshin will be promoted to strategic adviser to the presidential office, two Ukrainian officials said, bringing the former Ukrainian railway and arms czar much closer to the powerful president.

“For me it’s time for new challenges,” Kamyshin said in a post on X Wednesday after the Ukrainian parliament approved his resignation. “I will remain part of the team and will continue to do everything possible to bring our victory closer. I will continue to build the Arsenal of the Free World.” Herman Smetanin, the head of Ukroboronprom, Ukraine’s state defense conglomerate, is expected to take over the Ministry of Strategic Industries.

Ukrainian officials said Kuleba could take on an ambassadorial role in Africa, where he pleaded strengthening Ukraine’s diplomatic footprint to counter growing Russian influence in the South or in a key European institution such as NATO or the Council of Europe.

Ukraine is trying to make progress with anti-corruption reforms. It has climbed 40 places on Transparency International’s scorecard for tackling corruption in the past decade, despite two Russian military invasions. And experts don’t expect the upheaval to slow those efforts any further.

“Let’s be honest: There’s still an ongoing war, a very serious situation in the east. They’re still struggling to get the weapons and the support that they need in Ukraine from the United States and other partners in the west,” said Jonathan Katz, senior director of the anti-corruption, democracy and security project at the Brookings Institution. “There’s certainly some consolidation of power in scenarios like this, where you have an ongoing conflict.”