That's a good question — the Constitution defines treason as such: Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort
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Therefore, we should ask: is the firing on of American troops necessarily the waging of war on the several states?
No, obviously not — there are [American] troops who are not even citizens of the States.
In fact, you could raise an army and attack DC, burning it to the ground and definitionally it would not be treason.
I don’t think you understand the concept of “Levying War” . lol