 Both refused, so Lumumba turned to the Soviet Union for support.This led to growing differences with President Joseph Kasa-Vubu and chief-of-staff Joseph-Désiré Mobutu, as well as with the United States and Belgium, who opposed the Soviet Union in the Cold War.Lumumba was subsequently imprisoned by state authorities under Mobutu and executed by a firing squad under the command of Katangan authorities.