Okla. Stat. tit. 72, § 5

The provisions of this act shall be available to any disabled person who served during World War II, or any State of National Emergency as declared by the President of the United States, in the military or naval forces of any nation allied or associated with the United States, provided that the person was at the time of enlisting in the military or naval forces a citizen of the United States and is a citizen of the United States at the time he or she applies for the benefit of this act.