Appears legal.
10 U.S.C.
United States Code, 2010 Edition
Title 10 - ARMED FORCES
Subtitle A - General Military Law
PART I - ORGANIZATION AND GENERAL MILITARY POWERS
CHAPTER 15 - INSURRECTION
From the U.S. Government Publishing Office,
www.gpo.gov
CHAPTER 15—INSURRECTION
§332. Use of militia and armed forces to enforce Federal authority
Whenever the President considers that unlawful obstructions, combinations, or assemblages, or rebellion against the authority of the United States, make it impracticable to enforce the laws of the United States in any State by the ordinary course of judicial proceedings, he may call into Federal service such of the militia of any State, and use such of the armed forces, as he considers necessary to enforce those laws or to suppress the rebellion.