It's not our call, Lee
There was a time when I thought I could see sense in the Bush-Rumsfeld doctrine, but we need to draw a cautionary lesson from the mess that is Iraq. Saddam was damn-near as bad as they come, and yet replacing him has proven painfully difficult.
I think we as a nation need to calm down, spend less time dismissing the rest-of-the-world as irrational, and take more seriously our need to accomodate those who see things differently than we do. The American Way--capitalism, democracy, consumerism--might not be everyone's way.
The ultimate fate of Castro should lay with the Cubans, and the Mullahs with the people of Iran. If we choose to apply economic pressure, I guess that's our national perogative, but assasination is beyond the pale.