I looked it up, and enemy is defined very narrowly in the constitution, where have to be at war. We are not at war with Russia, but rather than being an ally, is considered a strategic adversary.
Looking at the laws it looks like he meets the criteria of "Seditious conspiracy", which only needs to be planned, and not carried out. Him asking Russia to hack into servers of Hillary Clinton who was Sec of State at the time is sufficient. Him now denying our own government intelligence about Russia hacking and instead siding with Russia adds to that. It's a 20 year sentence.
If two or more persons in any State or Territory, or in any place subject to the jurisdiction of the United States, conspire to overthrow, put down, or to destroy by force the Government of the United States, or to levy war against them, or to oppose by force the authority thereof, or by force to prevent, hinder, or delay the execution of any law of the United States, or by force to seize, take, or possess any property of the United States contrary to the authority thereof, they shall each be fined under this title or imprisoned not more than twenty years, or both.
(June 25, 1948, ch. 645, 62 Stat. 808; July 24, 1956, ch. 678, § 1, 70 Stat. 623; Pub. L. 103–322, title XXXIII, § 330016(1)(N), Sept. 13, 1994, 108 Stat. 2148.)
He also broke federal election laws "Foreign national shall not, directly or indirectly, make a contribution or a donation of money or other thing of value, or expressly or impliedly promise to make a contribution or a donation, in connection with any Federal, State, or local election." Not just with the emails. But also there seems to be continuing quid pro quo with foreign powers and Trump that is extremely troubling.