The streets of America shall run red with blood." The threat, delivered on one of those al-Qaeda videos that appear occasionally online, wasn't that unusual. Except that the man in it and three other videos spoke in perfect American English. His name is Adam Yahiye Gadahn, 28, a Californian who converted to Islam as a teen. Gadahn, who first appeared in an al-Qaeda video as a half-masked terrorist identified as "Azzam the American," was charged last week with treason for conspiring against the U.S. Now thought to be in Pakistan, he was added to the FBI's most-wanted list.
Treason is a rare crime. According...