The Islamic State (ISIS, ISIL or Da’esch) group claimed responsibility for the deadly April 9 clash in Basilan that left 18 soldiers and 5 militants dead, but the Philippine military is skeptical about the claim.

A statement from ISIS said the group was “able to detonate 7 trucks carrying soldiers,” according to a Reuters report Wednesday, April 13.

The statement also claims only 3 militants died in the 10-hour encounter Saturday in Tipo-Tipo, Basilan.

However, the military raised doubts on the claim, saying there were no trucks hit by bombs during the fighting, CNN Philippines reported Thursday, April 14.

Armed Forces of the Philippines spokesperson Brigadier General Restituto Padilla said the military believes it is part of ISIS’ propaganda in the country.

Padilla also said the military, so far, has yet to see a direct link between the Abu Sayyaf Group and ISIS.

Earlier, Rohan Gunaratna, the head of Singapore’s International Centre for Political Violence and Terrorism Research, said that the April 9 encounter was the first major ISIS attack on Philippine soil.

Gunaratna said that the group responsible for the attack was led by Isnilon Hapilon, who is seen as the leader of ISIS in the Philippines. He said the group is “no longer loyal to Radullan Sahiron, the Abu Sayyaf leader.”