Actually, no.
Although the G.I. Joe team (official designation: Special Counter-terrorist Group Delta) did recruit some of its personnel from other branches of the U.S. military and (particularly later in the comic book's run) occasionally "borrowed" from other countries' militaries, it has always been a unit of the U.S. Army.
-G
Indeed. International personnel were typically very rare, since security clearances would make it rather hard to have non-citizens in a unit that was as classified as the Joe team*; the two I recall were Big Ben, a SAS representative, and an Oktober Guard representative whose name I can't recall (they, being the Soviet equivalent of the Joe team, were themselves occasional opposition/allies for the Joes), and both of those were from fairly late in the toy line's release. Storm Shadow, aka Tommy Arashikage, was from Fresno, CA; he was actually in the same LRRP squad as Snake-Eyes and Stalker in Vietnam.
COBRA was more international, with Major Bludd (Australian?), the Baroness (some form of Central/Eastern European nobility, sort of Red Army Faction type), Zartan (unknown, presumed European), and Destro (Scottish) all being non-American, and many of the Drednoks were Australian or British. *Technically* Serpentor might count as being an American, having been decanted in Springfield, but that would be a matter for some debate, and it's not like he's a recognized citizen. The only major COBRA villains I recall being American were Dr. Mindbender and, ironically, Cobra Commander.
Now, there was Action Force, which was a rebranded G.I. Joe that was published in England and Europe. That may be what Cergorach is thinking of.
Brad
* - At least, that'd be my justification if I were Larry Hama and coming up with backgrounds for characters. It's relatively common for British and Americans to be loaned to the other's military for cross-training, and it's sort of possible to justify a Soviet exchange member based on the character appearing about the time of glasnost and perestroika (and the relative popularity of the Oktober Guard).