Philippine President Rodrigo Duterte apologized on Tuesday to Germany for the beheading of German hostage Jurgen Gustav Kantner, who was killed by Abu Sayyaf militants. Kantner was murdered after a ransom deadline lapsed on Sunday, and the extremists recorded a video of his beheading. He was kidnapped in November while sailing. Duterte said that an offensive against the extremists is currently underway. German Chancellor Angela Merkel has called Kantner's beheading an "abominable act." Duterte said on Tuesday that he has requested assistance from China in patrolling the international waters where Kantner was captured.