Russian leader <a href="https://www.businessinsider.com/vladimir-putin-just-did-donald-trump-big-favor-against-biden-2024-2">Vladimir Putin</a> is replacing his longtime defense minister <a href="https://www.businessinsider.com/sergei-shoigu-vladimir-putin-russia-ukraine-war-problems-2022-11">Sergei Shoigu</a>, 68, with an economist.