In a 25-minute video titled “A Call to Arms” posted to militant Islamic Web sites on Sunday, Al Qaeda’s American-born spokesman Adam Gadahn called on Muslims serving in the U.S. armed forces to emulate Army Major Nidal Malik Hasan charged with killing 13 people in Fort Hood, “Brother Nidal is the ideal role-model for every repentant Muslim in the armies of the unbelievers and apostate regimes.” Dressed in white robes and turban, Gadahn, known as Azzam al-Amriki, called for attacks on what he described as “high-value targets.” “You shouldn’t make the mistake of thinking that military bases are the only...