President Volodymyr Zelenskiy has named Ukraine's spy chief as his top adviser, placing a popular military leader at the heart of decision-making as Ukraine seeks to strengthen its defences against Russia and its hand in US-backed peace talks.
The appointment of Kyrylo Budanov, a decorated war veteran widely respected by Ukrainians, as presidential chief of staff marks a significant shift for a position traditionally occupied by a civilian mainly focused on domestic politics.
Budanov, 39, replaces longtime Zelenskiy confidante Andriy Yermak, a widely criticised power broker who resigned in November amid a corruption scandal that fuelled public anger as Ukraine fights for survival against Russia.
Zelenskiy will be hoping the appointment can help restore trust in his leadership and state institutions at a difficult moment, with Russia advancing on the battlefield and the US pressuring Ukraine to quickly end the nearly four-year war.
Writing on X, Zelenskiy said Ukraine "needs greater focus" on security, the military and diplomacy.
"Kyrylo has specialised experience in these areas and sufficient strength to deliver results," Zelenskiy wrote on X.
In a statement, Budanov said he had accepted the offer and would focus on the "strategic security of our state".
Later on Friday, Zelenskiy said he would appoint the current head of foreign intelligence, Oleh Ivashchenko, as the new military intelligence chief and that he also intended to replace the head of the border service.
Budanov has headed the Defence Ministry's Main Directorate of Intelligence (HUR) since 2020 and brings a track record of overseeing covert and other operations against Russian forces.
He has also led talks with Russia on the exchange of prisoners of war.
Budanov makes frequent media appearances and is known for his restrained style and often cryptic commentary about suspected Ukrainian actions inside Russia.
Yermak, Budanov's predecessor, was dubbed Ukraine's "grey cardinal" because of his behind-the-scenes power and influence.
He quit on November 28, hours after anti-corruption agents searched his home.
Investigators have been probing a purported $US100 million ($A150 million) kickback scheme in the energy sector allegedly involving Zelenskiy's former business partner and senior officials.
Yermak, who was also Ukraine's lead negotiator in peace talks, has not been named as a suspect.
But MPs and even some in Zelenskiy's party had demanded his ouster even before his home was raided, arguing that he bore responsibility as the president's right-hand man.
Ukrainian officials said Russian missiles struck a multi-storey apartment building in Kharkiv in the country's northeastern on Friday, leaving the building in ruins and injuring at least 25 people.
Photographs and videos posted online showed smoke rising from an area of vast destruction, with emergency crews making their way through rubble and large chunks of building materials.
But Russia's Defence Ministry said the Ukrainian reports were untrue, adding that the damage there was likely caused by the detonation of Ukrainian ammunition.
"Information about a supposed strike on the city of Kharkiv on January 2 by the Russian armed forces are not true," the ministry wrote on Telegram.
The ministry said the reports sought to distract world attention from a New Year's Eve strike on a hotel in a Russian-held part of Kherson region.
The area's Russia-installed governor told TASS news agency on Friday that the death toll in that incident had risen to 28.
