In a Detroit federal court today, the so-called "underwear bomber" pleaded guilty to trying to blow up a plane to avenge what he called "the US wreckage of Muslim lands and property." The evidence against Umar Farouk Abdul-mutallab was overwhelming. But there is some skepticism about yesterday's US claim that Iran plotted to assassinate the Saudi Ambassador to the US on American soil, working through a Mexican drug cartel. P.J. Crowley, a former spokesman for the US State Department, is now a research professor at George Washington University.