Help me under stand this!? please dumb it down for me!?

What part of it? I mean, Vietnam was a complicated war for us, but what is trying to be said is that we supported dictator after dictator, as they were anti-Communist, in a vain attempt to defeat the North. What these people did later on in their countries were things that hadn't been seen since Stalin in the 30s, when, mad with power, the leaders solidified their grip on the nation by killing off those that might oppose them.