Treason!

[DDySiegs]

6. Here is Section 2381 of Title 18 of the U S Code

This is the treason statute 18 USC, section 2381:

Whoever, owing allegiance to the United States, levies war against them or adheres to their enemies, giving them aid and comfort within the United States or elsewhere, is guilty of treason and shall suffer death, or shall be imprisoned not less than five years and fined under this title but not less than $10,000; and shall be incapable of holding any office under the United States

Note especially the last clause of the statute. In a sense violation of this statute amounts to a self executing impeachment (and conviction) when applied to a president.