2) It specifically addresses the question of the US and Congress. https://abe-winter.github.io/2019/10/18/tweason.html#can-a-t...
Even John Walker Lindh couldn't be charged with treason, and he had the weight of an actual AUMF against him.
What makes this case so interesting is it was treason vs a specific state not the entire USA.
“That levying an army may or may not be treason, and that this depends on the intention with which it is levied, and on the point to which the parties have advanced, has been also stated. The mere enlisting of men, without assembling them, is not levying war. The question then is, whether this evidence proves Col. Burr to have advanced so far in levying an army as actually to have assembled them.”
In the Burr case no men where actually assembled. “No evidence existed that either Bollman or Swartwout engaged in any military activity or violent acts.” I could be misreading this but I believe the military acts of a non violent nature could still qualify under this definition. Though, it’s stretching the definition of war to call such non violent acts war, such is the way of such things.
In any case I believe the line for treason is close to but before what could be called “open war.”
They arguably do, if either the war is levied under the authority of a Congressional aujorization, conditional or others, including the War Power Act, which effectively includes an open-ended conditional declaration of war, or the other side fights back, in which case it is levying war against the United States making it an enemy whether or not war is declared.
In practice, the former condition will almost invariably be adhered to though every President has denied it's Constitutional necessity (the NATO-Serbia war under Clinton being a notable exception), and the latter is even more certain.
> Even John Walker Lindh couldn't be charged with treason
He wasn't charged with treason, that doesn't mean he couldn't have been.