The U.S. defense chief says the violent influence of the Islamic State group could be emboldening militants in the southern Philippines, who last week killed 18 Filipino troops.

Defense Secretary Ash Carter compared the slain Filipino soldiers to U.S. troops buried at an American World War II cemetery in Manila as he laid a wreath there Thursday.

Carter says their deaths are another reason why the IS must be destroyed.

Philippine Defense Secretary Voltaire Gazmin says the Abu Sayyaf militants who clashed with the Filipino troops were trying to affiliate themselves with the IS in Syria and Iraq but there has been no evidence that the Middle East-based group has a presence in the country.

The Philippine military deaths were its largest single-day combat loss this year.