RN Buccs were sent on combat sorties from the carrier Ark Royal against Guatemala in 1971 (I think) because of the threat of invasion of British Honduras (now Belize). The Buccs were launched and flew through US territory (over water), but were picked up by US radar and were intercepted by American jets and were told to break off, but the Buccs flew down low and eventually the Yanks gave up. The Buccs didn't actually fire their weapons in anger as the operation was called off before the target area was reached.
Regarding Buccaneers in exercises against the Americans, I once heard a story by an ex-RAF Bucc driver who told me about exercises conducted off the coast of Scotland, where the UK was under threat of invasion by a foreign power, represented by a US carrier task force - I can't remember what year this was, but before the carrier got withing range of launching its aircraft, Buccs from 12 Sqn were launched from Lossiemouth on the Moray Coast of Scotland and sped under the US radar and gave the Yanks a heck of a surprise by popping up undetected and giving a high speed fly-over of their carrier before speeding back to Lossie, counting the carrier as a 'kill' on return!