Re: Unfortunately ...
"our Constitution only provides for that charge in times of War."
I don't think that's entirely true, and because I'm in need of distraction, I'm going to overanalyze why I think that. You can probably skip this when you get bored.
The relevant part of the American constitution reads as follows:
"Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court. The Congress shall have Power to declare the Punishment of Treason, but no Attainder of Treason shall work Corruption of Blood, or Forfeiture except during the Life of the Person attainted."
So it appears that treason has two definitions, neither of which includes anything like "in time of war". I'd argue that one of them at least implies war: "adhering to their Enemies, giving them Aid and Comfort", but you can have enemies without having war with them, or you can have enemies with whom you can't be at war in the international law sense because the enemies aren't states. But fine, I'll restrict this to define enemies as countries the U.S. declared war on. Somehow, I think people would define it differently if someone was being charged after working with a non-state organization which wished to destroy the U.S., but we'll leave that alone.
The reason I can do that is that there is another option listed there: "levying War against them". Once again, we have a word without a clear definition. War could mean a state of war declared by a recognized country, but I don't really think that's an honest description of how it's used. Let's try a dictionary. While it includes "Organized, large-scale, armed conflict between countries or between national, ethnic, or other sizeable groups, usually involving the engagement of military forces.", it also includes "Any conflict, or anything resembling a conflict.". It appears the dictionary isn't going to help much in getting a firm definition of what is and isn't war.
Let's instead try history. What have generally been called wars? The traditional country-fights-country things, of course, but several smaller things too. Civil wars, which don't involve a declaration of war since each side considers the opposition government at least illegitimate and often beneath consideration. Wars which didn't have a formal declaration (Korean War, Iraq War). Campaigns involving smaller wars (war on terror). Not to mention that it's also frequently used by people who aren't governments (I.E. "we are at war with [something they don't like]". If these are wars, then perhaps "levying War against them" is easier than it seems. Maybe even saying that you intend to be at war with the U.S. is enough. Maybe an act similar to one taken in a war is enough. On that basis, a violent attack on a government institution might be sufficient, as that's certainly enough to start a war if a country did it and has certainly started an armed conflict when a group of people did it.
I'm done now. I think the original interpretation is incorrect. I need to sleep.