US law has traditionally held that if both parents are US citizens then the child is a natural-born US citizen regardless of where in the world they are born. This was specifically in support of diplomats, military, etc. I am not aware of a context in which this wasn’t true.

The only complicated area in law is when only a single parent is a US citizen and the child is born overseas. This was a consequence of the 20th century reality that the US had vast numbers of military personnel stationed globally.