The term "enemy" in the U.S. Constitution's definition of treason is generally considered to be a term of art that means a party against whom Congress has authorized the use of military force or a declared war.
The only such country in existence at this time, to the best of my knowledge, is North Korea. Terrorist organizations which had affiliated involved in the 9-11 attacks (including ISIS and Boko Haram) are also covered.
Russia is not an "enemy" of the United States, within the meaning of the constitutional definition of treason. Neither are any individuals or corporations in Russia, unless they are affiliated with a 9-11 terrorist organization.
An important statutory definition of "enemy" might also be considered informative to a court presented with this question, which is slightly broader (as it requires "hostilities" but does not require a full fledged war and does not require Congressional action):
According to 50 USCS § 2204 [Title 50. War and National Defense;
Chapter 39. Spoils of War], enemy of the United States means any
country, government, group, or person that has been engaged in
hostilities, whether or not lawfully authorized, with the United
(3) the term "person" means
(A) any natural person;
(B) any corporation, partnership, or other legal entity; and
(C) any organization, association, or group.
In this context, "hostilities" would generally mean physical warfare acts like shooting Americans, or blowing up American property, in a warlike manner.