Sort of. The U.S. signed Article III, but not IV. III is the section that prohibits expanding bullets, and IV limits the prohibition to conflicts between sign

Sort of. The U.S. signed Article III, but not IV. III is the section that prohibits expanding bullets, and IV limits the prohibition to conflicts between signatories. So it's clear that the U.S. is bound by Hague, but it's also arguably clear that Hague doesn't apply to any conflict that the U.S. has been involved in in the past decade. Terminal ballistics is the mother of all holy wars. There are undending arguments over caliber, weight, soft point vs. hollow point vs. JHP, etc. Expanding bullets pretty useless against body armor, but so are pistols in general, because AFAIK the U.S. military doesn't issue armor-piercing pistol ammunition. Besides, any sort of infantry engagement will rely on 5.56 rifles, and the standard M855/M855A1 ammo, while not strictly defined as "armor piercing", does contain a steel penetrator and is quite effective against body armor at close-ish ranges. Nevertheless, the U.S. military very much believes in the usefulness of hollow points in urban/CQ environments, and in fact the Army is now issuing hollow point bullets for the M17 and M18 service pistols. Presumably this ammo would not be used in a conflict against uniformed soldiers from a fellow Hague signatory state.