It was Richard Nixon's plan to phase out US troop involvement in the Vietnam War.
Explanation:
Richard Nixon's plan for ending American involvement in the Vietnam War was to increases troop levels of the Army of the Republic of Vietnam, train and equip them, and have them replace American troops which would be phased out over a two-year period (although air support would remain in place).the plan called "Vietnamization". was put into place in 19691969.
The plan ran into a number of setbacks including the expansion of the war into Cambodia and the unavailability of more suitable conscripts from South Vietnam. The Nixon administration stopped using the term entirely by 1972