If we're seen to side with a leadership that does not represent the Iranian people, it may help galvanize the people into acting against their leaders. If we side with the dissidents, we give the current government more anti-American ammunition -they can claim that any anti-government protests are simply the work of American influence. The problem, and it's one that I know some here will have a very hard time grasping, is that the Iranian people have very good reasons not to trust our government.