Don't have much of a sense of proportion bracketing the ones you mention with the mass murdering communists and Hitler,do you? Pinochet was only responsible for 30,000 deaths comapred to the millions of victims of the one I mentioned. Even Bush was only responsible for a relative handful of deaha in comparison.
As for Nixon, I quote "Although Nixon initially escalated America's involvement in the Vietnam War, he subsequently ended U.S. involvement by 1973. Nixon's visit to the People's Republic of China in 1972 opened diplomatic relations between the two nations, and he initiated détente and the Anti-Ballistic Missile Treaty with the Soviet Union the same year. Domestically, his administration generally embraced policies that transferred power from Washington to the states. Among other things, he launched initiatives to fight cancer and illegal drugs, imposed wage and price controls, enforced desegregation of Southern schools, implemented environmental reforms, and introduced legislation to reform healthcare and welfare. " which,again,is better ghan the ones I mentioned and not necessarily a reason for eternal damnation.
Apart from Vietnam Nixon escalated the war into neighbouring Cambodia and dropped more bombs on that country than were dropped on Dresden in WW2. His decimation of Cambodia also allowed the murderous Pol Pot regime to take over.
LBJ gave US forces carte blanche to accelerate the Vietnam war after JFK's assassination.
This was a policy which his murdered predecessor completely disagreed with and resulted in years of killing and atrocities.
Pinochet tortured and killed thousands of his own people and Baby Bush invaded Iraq on the pretext that Saddam Hussein was involved in 9-11 even though his own expert advisors told him categorically he wasn't.
The thing I don't understand is you saying Pinochet wouldn't deserve to be damned because he killed less than Hitler and Stalin - Is there a degree of murder or torture that is acceptable?
As for Thatcher she ignored early warnings from her own intelligence that the Argies were going to invade the Falklands. She could have prevented the invasion but instead she allowed it to happen and then launched the task force. Her popularity rating was rock-bottom before the war but sky-high afterwards when she won the election at a canter....