There have been militant Islamists in the Mindanao area for decades. They are very fluid in their support. In the last while they were said to be a cello Alquaida (sp) but now seem to moving towards the next best flavour, Islamic State. 
Duerte could not eliminate them when he was the Mayor of Davao and later Governor of the region because his storm troopers could not penetrate Al Sayef.