AR670-1 is very clear on this subject, and I follow the regs. If I am attending a formal military function, I wear my US Army mess dress. If I am attending a formal civilian function I wear civilian attire. As a matter of principle I never wear my mess kit to a civilian function.

In my entire life I have only once broken with this self-imposed rule. Four years ago I received an invitation to a private, white tie, function in London. The invitation said "white tie, uniform, decorations". Two quick telephone calls and it was revealed that the event was being covertly underwritten by the Syrian government.

So, of course, I wore my US Army mess uniform to this otherwise civilian event. The only other uniform present that evening was worn by a brigadier in the British Army and, as it turned out, for exactly the same reasons.

Some times we are not "two nations separated" by anything at all.