When South Vietnam and America did not keep their promise to hold an election and unite the two halves into one country, Hồ led Vietnam into a military and political struggle to bring the rice fields of the South under his Communist rule. Two decades of war followed, killing millions of Vietnamese. The United States supported South Vietnam with military aid, while the Soviet Union (led by Nikita Krushchev and then Leonid Brezhnev) and People's Republic of China (led by Mao Zedong) continued to support North Vietnam's war effort.