That was a very narrow window of time, mostly the time between the fall of the USSR ending the Cold War up to 9/11, so about a 10 years period since the end of WW2.

Before that the USA was aiding and fostering violent dictatorships, helping them to perform coups all around if they were amenable to the US's interests (aka: they were anti-commies) like in Latin America, Iran itself, etc.; bombing countries where their right-wing coups failed like in Vietnam during its independence period after French rule, for example.