replacing influential Vasyl Malyuk and nominating Maj-Gen Yevhenii Khmara as acting head. The SBU is primarily concerned with internal security and counter-intelligence and, since the beginning of Russia's full-scale invasion in 2022, it has also played a prominent role in assassinations and sabotage attacks deep inside Russia. Malyuk, who had run the SBU since 2022, gained a reputation for overseeing successful operations against Russia and for purging the SBU from alleged Russian double agents. The latest reshuffles are the latest in a long series made by Zelensky since the start of the war.

Malyuk's name is known across Ukraine. After all, last June he co-ordinated the daring "Spider Web" attack, which saw more than 100 Ukrainian drones struck air bases deep inside Russian territory. Khmara, his replacement, was also involved in the preparation of that operation. So it did not come as a surprise that Malyuk's dismissal earlier this week was widely criticised within Ukraine, including by several high-profile military commanders. The impression that the decision made by President Zelensky was short-sighted was cemented by reports that Malyuk had initially refused to step down voluntarily.

Although he has been dismissed from the position of SBU chief, he has been asked to continue leading special operations against Russia. Ukraine needed more "asymmetric operations against Russian forces", Zelensky said, adding that Malyuk was "best at this".

Khmara's appointment has gone some way in quelling fears about the SBU's future effectiveness. But former SBU operative Ivan Stupak argues his reputation - though solid - is limited to a certain sphere and that it is unclear whether he will be able to translate his experience to running the wider SBU. Stupak also believes that Malyuk's dismissal is connected with the appointment of former spy chief Kyrylo Budanov as Zelensky's new chief of staff. (BBC)