As part of the Nixon administration's policy of Vietnamization , the U.S. military - trained South Vietnamese forces to take over combat responsibilities from U.SS troops imposed martial law in North Vietnam installed a puppet government in South Vietnam shared military technology with North Vietnam

The question is asking about the policy of Vietnamization during the Nixon administration. Vietnamization was a policy of the Richard Nixon administration during the Vietnam War to end U.S. involvement in the war and expand, equip, and train South Vietnam's forces and assign them an increasing combat role, at the same time steadily reducing the number of U.S. combat troops. Therefore, the correct answer is that the U.S. military trained South Vietnamese forces to take over combat responsibilities from U.S. troops.