It needs a wise supreme leader, and wise Islamic scholars who can discern who is a candidate that fits Islamic standards and who is not. All these things, if they cannot be understood by the U.S., then it would be better to focus on perfecting it's own system. Iran, the most perfect democracy in the Muslim world, would not export it's model into Saudi Arabia by force. Last but not least, Saudi Arabia is sunni, and shia Islam has the power and discipline sunni Islam cannot provide unless by the use of force and repression, which doesn't exist in the I.R. of Iran.
Australian police arrest 5 over shooting 'linked to terrorism' (Reuters)
from the article: The mysteries of American logic