A nineteen-year old Somali Muslim named Mohamed Osman Mohamud was arrested Friday in Portland, Oregon, just as he was trying to blow up a van loaded with explosives at a Christmas tree lighting ceremony. The explosives were fakes that agents who were tracking Mohamud’s activities supplied to him; as they moved in to arrest him, he kicked at them and shouted, “Allahu akbar!” Although the explosives were fake, “the threat was very real,” according to Arthur Balizan, special agent in charge of the FBI in Oregon. “Our investigation,” said Balizan, “shows that Mohamud was absolutely committed to carrying out an...