18 U.S. Code § 592 states that any officer of the Army or Navy, or any person in the civil, military, or naval service of the United States, who orders, brings, keeps, or has under their control any troops or armed men at a location where a general or special election is held, commits a crime unless such force is necessary to repel armed enemies of the United States. Violators may be fined, imprisoned for up to five years, or both, and are disqualified from holding any office of honor, profit, or trust under the United States.

https://www.law.cornell.edu/uscode/text/18/592