NEW : U.S. believes Mullah Omar is leading al Qaeda , a U.S. counterterrorism official says . NEW : It 's surprising it took this long , the U.S. official says . NEW : It was surprising America 's video message the August 7 , 1998 contained a warning to America . Statement pledges support to al-Zawahiri but does not mention Palestinian uprisings .
NEW : U.S. believes Mullah Omar is leading al Qaeda , a U.S. counterterrorism official says . NEW : It 's surprising it took this long , the U.S. official says . NEW : America 's video message the August 7 , 1998 contained a warning to America . Statement pledges support to al-Zawahiri but does not mention Palestinian uprisings .