hostile force or person
(c) The term “hostile force or person” means any nation, any subject of a foreign nation, or any other person serving a foreign nation (1) engaged in a war against the United States or any of its allies, (2) engaged in armed conflict, whether or not war has been declared, against the United States or any of its allies, or (3) engaged in a war or armed conflict between military forces of any origin in any country in which a person covered by this chapter is serving.