We have forced NATO to adopt our rifle cartridges twice. First the .308 (7.62X51 NATO) and then the .223 (5.56mm NATO). At the time we adopted the 9mm, it was to keep the NATO folks from bitching too much about the change from 7.62 to 5.56mm, after most of them had just got finished buying the 7.62 rifles! At the time, we had a lot of geniuses in charge who thought of the service pistol as a "badge of office" rather than a useful battlefield weapon. Well, Iraq and Afghanistan have changed this line of thinking, and a lot of special ops people (and others) have gone back to the .45 ACP, which we should never have abandoned in the first place.