 By the beginning of January 1968 , the U.S had deployed 331 @,@ 098 Army personnel and 78 @,@ 013 Marines in nine divisions , an armoured cavalry regiment , and two separate brigades to South Vietnam . They were joined there by the 1st Australian Task Force , a Royal Thai Army regiment , two South Korean infantry divisions , and a Republic of Korea Marine Corps brigade . South Vietnamese strength totaled 350 @,@ 000 regulars in the Army , Air Force , Navy , and Marine Corps . They were in turn supported by the 151 @,@ 000 @-@ man South Vietnamese Regional Forces and 149 @,@ 000 @-@ man South Vietnamese Popular Forces , which were the equivalent of regional and local militias . 
