You have to look at the legal definition as put down in the Constitution...
Treason. A breach of allegiance to one's government, usually committed through levying war against such government or by giving aid or comfort to the enemy. The offense of attempting by overt acts to overthrow the government of the state to which the offender owes allegiance; or of betraying the state into the hands of a foreign power. Treason consists of two elements: adherence to the enemy, and rendering him aid and comfort. Cramer v. U. S., U.S.N.Y., 325 U.S. l, 65 S.Ct. 918, 9327 89 L.Ed. 1441. See 18 U.S.C.A. § 2381. A person can be convicted of treason only on the testimony of two witnesses, or confession in open court. Art. III, Sec. 3, U.S. Constitution
breach of allegiance, aid and comfort, subversion. Yep, still got no evident problems there. Adherence to the enemy is pretty broad, standing on their shores and subverting your fellow citizenry is right up the alley. Treason. pure and simple.
Oh, I might add, for a little insight on how little it takes to be treasonous, that John Kerry did something in meeting with the NorthVietnamese that back then evidently was not actionable. Today it would have him before a firing squad and he merely met with them in wartime. Unpatriotic here is so blatently inadequate a word as to be laughable.