Moscow continues to shuffle its senior military officials, appointing 55-year-old Air Force Gen. Sergei Surovikin to lead Russia's faltering "special military operation" in Ukraine, the third new reassignment in a week. The announcement marked the first official appointment of a single commander for the entire Russian force in Ukraine.

The change follows the reported sacking of the commanders of two of Russia's five military regions last week, as its forces have suffered a series of dramatic reverses in northeastern and southern Ukraine in recent weeks.

Russian Defense Minister Sergei Shoigu appointed Surovikin after critics demanded a redeployment of troops in Ukraine given the defeats faced by Russian forces of late.

The ministry did not say who, if anyone, Surovikin was replacing.

British military intelligence said in April that Gen. 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 "centralize command and control."

Surovikin 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.

War reporters, field commanders and the Wagner Group, a private Russian mercenary force, all welcomed the appointment, according to Russian media reports.

He will face major challenges given the successes of Kyiv's swiftly advancing forces in retaking Ukrainian territory.