Do dirty Duterte.
The insurgents melt away after the fight. There is no uniformed army to seek out and destroy. IMHO you will need to expand the punishment to the family of the terrorists. Sort of how Israel will bulldoze the house of a suicide bomber. Some greater price needs to be paid than simply killing the terrorists. After all, in their world view, you are simply giving them the only surefire way a muslim can enter heaven, via martyrdom. Bring the pain to their families. That type of punishment can be done via martial law. He could also borrow a page from our Marines. We used to bury the dead in the Southern Philippines with a slaughtered pig. That seemed to dampen the Islamist’s desire to fight back in the day.
I want Duterte to kill every single terrorist in his country. Given a choice, rescue the hostages too, but the priority should be dead terrorists.