Refusal or failure to plead.
Article 21
ART. 21. Refusal or failure to plead.—When an accused arraigned before a court-martial fails or refuses to plead, or answers foreign to the purpose, or after a plea of guilty makes a statement inconsistent with the plea, or when it appears to the court that he entered a plea of guilty improvidently or through lack of understanding of its meaning and effect, the court shall proceed to trial and judgment as if he had pleaded not guilty.