The ISIS leader responsible for the siege of Marawi city in the Southern Philippine island of Mindanao, may have slipped through Filipino troops. This is despite the progress of the Philippine army in retaking the city from terrorist hands.

How did the ISIS leader escape?

The Filipino-born, ISIS leader named Isnilon Hapilon, is suspected to have escaped the tightening ring of Filipino troops as military intelligence have failed to detect his presence in the city. The news of Hapilon's escape was reported by Lieutenant General Carlito Galvez, head of the Mindanao command.

Reports by Digital Journal cited DZBB radio station as indicating that the ISIS leader managed to escape the city during the height of the fighting. The Philippine army was caught off-guard by the speed of the terrorist group which took hold of the city and were able to only sustain a stubborn resistance.

Due to the rapid movement of the jihadists, Philippine President Rodrigo Duterte declared Martial law in the entire island of Mindanao. Droves of Filipino troops were immediately deployed into the Marawi area and the fighting commenced. The progress was slow and difficult due to ISIS fighters using trapped civilians as human shields.The untrained local soldiers in urban warfare was also a major factor for the terrorists inside Marawi.

Due to this, Duterte allowed the Philippine military to seek help from U.S. troops that are stationed in the country. American soldiers, who are part of the military drills being conducted in the Philippines agreed to help but only to provide surveillance and advisory support. In the last week, Filipino troops have managed to push the terrorists into small pockets in the city.

$5 million reward for ISIS leader

Washington placed a $5 million bounty on the fleeing ISIS leader, Isnilon Hapilon. The U.S. included this jihadist leader on America's most wanted list. According to U.S. Intel relayed to the Philippine military, Hapilon was delegated by the ISIS leadership to be "amir" of an Asian Caliphate that they plan to start in Mindanao.

Hapilon joined forces with the Maute group, a local radical Islamist sect and the Abu Sayyaf, a local terrorist group that has links to Al-Qaeda and ISIS.

The siege of Marawi City is apparently at its end stage as Filipino soldiers are in the process of destroying the remaining pockets of resistance in the city. However, due to the archipelagic terrain of the Philippines, policing hundreds of islands against terrorist infiltration will be a constant problem for the Philippine army.