However, then there's this.

'THIS LEGISLATION IS COMMONLY KNOWN AS "THE PROXMIRE ACT"

The Proxmire Act is contained in Chapter 50A of the US law code, Title 18 (Crimes and Criminal Procedure), Part I (Crimes). Section 1091 deals specifically with Genocide. The law implements the United Nations' Convention on the Prevention and Punishment of the Crime of Genocide (UNCG) in the U.S.
It states in part:

(a) Basic Offense. - Whoever, whether in time of peace or in time of war, in a circumstance described in subsection (d) and with the specific intent to destroy, in whole or in substantial part, a national, ethnic, racial, or religious group as such -
kills members of that group;
causes serious bodily injury to members of that group;
causes the permanent impairment of the mental faculties of members of the group through drugs, torture, or similar techniques;
subjects the group to conditions of life that are intended to cause the physical destruction of the group in whole or in part;
imposes measures intended to prevent births within the group; or
transfers by force children of the group to another group; or attempts to do so, shall be punished as provided in subsection (b).

(c) Incitement offense. - Whoever... directly and publicly incites another to violate subsection (a) shall be fined not more than $500,000 or imprisoned not more than five years, or both.'