The chief of Russia's General Staff, General Valery Gerasimov, is a close ally of Defense Minister Sergei Shoigu. (file photo)
Russian Defense Minister Sergei Shoigu takes part in a rehearsal for the Victory Day parade on Red Square in central Moscow in 2019.
U.S. President Joe Biden (left) and Ukrainian President Volodymyr Zelenskiy hold a joint news conference in the East Room of the White House in Washington on December 21.
A Ukrainian artilleryman carries a 122-mm shell for a 2S1 Gvozdika self-propelled howitzer at a position along the front line near Bakhmut on December 10.
Winter war in Ukraine: "It does suck, it's just going to be cold and wet, and there's no doubt about it," one former U.S. general said.