The US.
The United States went into war with Vietnam in the year 1965.
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President Eisenhower sent US troops to Vietnam in 1955, President Ford pulled out the last US troops in 1975.
President Eisenhower.
Several. Australia, New Zealand, The Philippines, Thailand, and the Republic of Korea (South Korea) sent troops to Vietnam.
In the 1950s and 1960s Eisenhower and Kennedy sent US soldiers to South Vietnam. In 1965 President Johnson sent the US Marines.
President Dwight Eisenhower
Well before any US troops were sent to Vietnam. The Korean Conflict kicked off in 1950, and the ceasefire was signed in 1953 (although the conflict remains ongoing). The first American troops didn't arrive in Vietnam until 1954.
United States Marines were sent March 8, 1965.
Special Forces (Green Berets) were sent to Vietnam by President Kennedy in the early 1960's. REGULAR US ground troops were sent in 1965.
First ground troops were sent to Vietnam in 1965.