FILE -- In this Feb. 20, 1991 file photo, some Afghan mujahedeen receive training for possible gas warfare during the Gulf War at their camp in Khafji near the Saudi-Kuwait border. Twenty five years after the first U.S. Marines swept across the border into Kuwait in the 1991 Gulf War, American forces find themselves battling the extremist Islamic State group, born out of al-Qaida, in the splintered territories of Iraq and Syria. The Arab allies that joined the 1991 coalition are fighting their own conflicts both at home and abroad, as Iran vies for greater regional power following a nuclear deal with world powers. (AP Photo, File)