Trump has options on Iran, but first must define goal

It has been 10 days since Trump said the United States was "locked and loaded" and ready to "come to the rescue" if Iran's clerical state kills demonstrators who have taken to the streets in major numbers. Since then, Trump has kept threatening a military option, even as hundreds of people have died, according to rights groups. Iran has been a sworn foe of the United States since the 1979 Islamic revolution toppled the pro-Western shah. The downfall of the Islamic republic in power since then would transform the Middle East.