Well, the various Banana Wars topped out with around 2500 troops landed.No invason? Mmm, how about interventions such as in the Domincan Republic, the Bay of Pigs? Pretty bloody close IMO.
Small Beer to to 1956 and 1968. Hell, the Soviets had more than that as 'Military Experts' in North Vietnam during the War
You do know that no US Troops landed in Cuba, right?