Eisenhower, Kennedy, LBJ, and to a certain extent Nixon & Ford sent US Military men to South Vietnam.
The term "troops" can be misleading. In the US Army Armored Cavalry Squadron's, TROOPS are companies commanded by a Captain. Example: "F" Troop, "C" Troop, etc.
Military men sent to Vietnam under the Eisenhower administration were combat troops; but acting in an advisory manner. Kennedy sent combat troops; also acting in an advisory manner, but also killing enemy soldiers in special operations. That's combat!
If you're looking for the term that describes regular US infantrymen, be they US Army or US Marine Corps; then President LBJ sent in "Regular" US infantrymen/marines, armor crewmen (known as tankers to civilians), and artillerymen in 1965.
NON-combat troops are cooks, truck drivers, medics, mechanics, clerks, and in Vietnam Military Policemen, to name a few.
Carter
They were mad. Santa Anna Mexican president at that time sent 6000 troops to Texas. In conflict there were couple of battles.
President Eisenhower.
The first George Bush.
President Clinton sent troops to Haiti and Bosnia.
President Dwight Eisenhower
Lyndon Johnson was the president when large numbers of US troops were first sent to Vietnam.
George Bush Senior did.
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.
NIXON
Somalia
US President Ronald Reagan sent US troops to Beirut, Lebanon on 20 Aug 1982.