What Do the New Attacks on U.S. Embassies Mean?

Protesters stormed the U.S. Embassy in Yemen this week and set fire to a building. Like the mob in Egypt on Tuesday, they tore down the American flag. Reports are also circulating of a separate protest in Tehran today with about 500 Iranians chanting "Death to America." Meanwhile, a onetime mentor of Osama bin Laden called on his followers to replicate what happened in Libya and Egypt.