First off, it's not solely the US's freedom to make the world a dictatorship as they see fit, all the other countries, their governments and the people of those nations have to let them do it..... The US can turn themselves into a dictatorship if they please, but they can not turn the rest of the world into a dictatorship without the help of other nations and their governments.
The US already had a hell of a time trying to get everybody behind their last two wars. The US already had a hell of a time trying to PR and cover their asses for all the things they have lied about or justified for their own reasons...... I believe it'll be an even harder job for them to keep their allies right along beside them if something like the above occured. They're gonna need some really good solid evidence on who did it before they get any kind of support like they did in the past. They already screwed up with crying wolf twice before.
As I see it, the US can have another attack, they can get nuked, they can get nuked all over the place for all I care..... but they created the situation in the first place. Sometimes people have to learn the consequences of their own actions on their own...... like a kid who always has their mommy or daddy covering their asses everytime they do something wrong.
But if Hitler and Nazi Germany couldn't get the whole world to follow their ways, I sure as hell doubt the US has any chance. And besides..... there are way too many ways at present to prevent the US from doing any such thing.