Philippine soldiers walk past the damage area of a catholic cathedral in Jolo town, sulu province, in southern island of Mindanao on January 28, 2019, a day after two explosions tore through the cathedral. - Investigators probing the Catholic cathedral bombing that killed 21 people in the Philippines' restive south said January 28, a group tied to notorious Islamists Abu Sayyaf is the prime suspect. (Photo by NICKEE BUTLANGAN / AFP)        (Photo credit should read NICKEE BUTLANGAN/AFP/Getty Images)