Wightsparker
LE
It is. That's why I used to go across the river into Canada back in the day to get served in bars legally. Or might have used something called a fake ID. Allegedly.
Exercise Purple Star, 1996, involving personnel in North Carolina.
Exercise seems to have worked quite well, and and the question of legal age drinking was - as I recall - made crystal clear to the UK participants.
With the main exercise completed, there still the need to get people back to the UK. At the US Marine Corps Air Station, Cherry Point, there were large numbers of UK personnel waiting to go home. Numbers reduced daily.
I recall a morning briefing during this latter period when a RMP officer reported a problem with British Army personnel having gone downtown. (they were reported as being Paras.)
They apparently went into bars and drank alcohol, although some of them were actually under 21!
It worked for a while, and then they were refused further drinks. They apparently tried again at other bars, but the bush telegraph worked and they found themselves out of luck.
The RMP officer then reported that three of these Paras walked back to Cherry Point, but on the way broke into the Motor Pool compound and got access to the battery acid top-up store, from which they drank liberally.
The morning briefing audience were appalled.
The RMP officer then reported: "I understand that they are all being charged this morning".
There was a moment of silence before a roar of approval. Despite evidence to the contrary, it appeared that the RMP did have a sense of humour.
I'm sure the ship's company of HMS Queen Elizabeth were briefed about under age drinking in the USA.