In his nightly video address, Zelenskiy said he spent the day meeting his military leadership and government and that experienced "combat commanders of this war" would be taking on new duties. The country is closing in on two years of war since Russia's full-scale invasion.

As deputy chiefs of staff under Syrskyi, Colonel Vadym Sukharevskyi would take charge of unmanned systems and development of the use of drones by soldiers, while Colonel Andriy Lebedenko would focus on technological innovation of army and combat systems, Zelenskiy said.

Zelenskiy said he had also approved nominations of three brigadier generals as deputies of the General Staff of the Armed Forces of Ukraine - Volodymyr Horbatyuk, who would run operations and management, Oleksiy Shevchenko, in charge of logistics, and Mykhailo Drapatyi on training.

"We continue the reboot of the management team," Zelenskiy's Telegram channel quoted him as saying in the address.

Syrskyi, previously commander of ground forces, was promoted on Thursday to overall command of Ukraine's 800,000-strong armed forces. He later singled out drones and electronic warfare as examples of new technology that would help Ukraine achieve victory.

Ukraine has failed to recapture significant territory since late 2022 and faces a potential disruption in military aid supply from the United States, its biggest backer.

(Reporting and writing by Elaine Monaghan in Washington; Editing by Frances Kerry)