Russia's Defence Ministry on Saturday named Air Force General Sergei Surovikin as the overall commander of Russian forces fighting in Ukraine, Moscow's third senior military appointment in the space of a week.
The change follows the reported sacking earlier this week of the commanders of two of Russia's five military regions, as its forces have suffered a series of dramatic reverses in northeastern and southern Ukraine in recent weeks, news agency Reuters reported.
The ministry did not say who, if anyone, Surovikin was replacing.
British military intelligence said in April that General Alexander Dvornikov had been appointed to take charge of Russian forces in Ukraine, almost two months after Moscow began what it calls its "special military operation", in an attempt to "centralise command and control".
However, Moscow itself has not specified that anyone is in overall military command of the operation.
Surovikin, 55, has led Russia's Air and Space Forces since 2017. According to the ministry's website, he commanded a guards division stationed in Chechnya in 2004, during Moscow's war against Islamist rebels, and was awarded a medal for his service in Syria in 2017.