"How about the time we attacked Cuba "
First of all, the United States never attacked Cuba. Where did you get that from? The CIA supported a Cuban exile group and their efforts failed in the "Bay of Pigs" invasion. The reason the Cuban exiles failed was because Kennedy refused to allow US air support or any direct involvement by US forces. Again, Cuba under Soviet control represented a SERIOUS THREAT to national security. Cuba is just off the coast of Florida! The Soviets built nuclear missiles in Cuba that could wipe out half the US within minutes, before the US could assess and respond.
Manuel Noriega obtained power in Panama on his own accord. He did sell information to the CIA but would provide favors to anyone if it served his own interests. He turned Panama into a narcotic state and again this was not in the interests of the United States.
Viet Nam, what "oil" are you talking about??? The US was helping South Viet Nam fight the aggressive communists in North Viet Nam. Allowing the communists to control all of Viet Nam was seen as possibly allowing them assert control over the entire South East Asian region including Thailand which was termed the "Domino Effect". Please refer to my "history lesson" about the Cold War to see why this was not acceptable. Actually, read the history lesson to answer all your questions of what guided US foreign policy in the past. It was the COLD WAR. People don't understand how serious it was apparently. I am thankful naive people like you weren't making the decisions back then.