delivered the opinion of the Court.
A special court-martial composed of a military judge sitting alone convicted appellant, pursuant to his pleas, of unauthorized absence (UA) and missing a military movement, in violation of Articles 86 and 87, Uniform Code of Military Justice, 10 USC §§ 886 and 887, respectively. Appellant was sentenced to a bad-conduct discharge, confinement for 80 days, forfeiture of $500.00 pay per month for 2 months, and reduction to pay grade E-1. The convening authority approved the sentence as adjudged, but suspended all confinement in excess of 75 days for 6 months from the date of trial. The Court of Criminal Appeals affirmed. 47 MJ 545 (1997).
On appellant’s petition, we granted review of the following issue:
WHETHER THE LOWER COURT ERRED IN FAILING TO RECOGNIZE “NECESSITY” AS AN AVAILABLE DEFENSE IN MILITARY PRACTICE.
For the reasons stated below, we will affirm the decision of the Court of Criminal Appeals.
*366I
Appellant was assigned to the USS FAH-RION, which was scheduled to deploy for more than 5 months, beginning on June 27, 1995. On that date, appellant failed to return from authorized leave and report to his ship, located at Mayport, Florida. He remained absent until on or about December 5, 1995, when he turned himself in to authorities at Great Lakes Naval Station.
At trial, appellant pleaded guilty. His responses to the providence inquiry provided a factual basis for all the elements of the charged offenses. However, in an unsworn statement during sentencing, appellant noted that in March 1995, he and his wife found out that she could not have children. She suffered from depression and took Prozac, an antidepressant drug. He added that she previously had an operation that made “stress a danger to her health.” He also stated: “And at the time I went UA I felt that her depression might kill her from the stress if I went on the UNITAS deployment.”
On appeal, appellant argues that the defense of necessity should be applied either as a matter of common law or as a military adaptation of the common-law defense. He claims that this statement reasonably raised the possibility of a necessity defense, which established a substantial conflict with his pleas and rendered them improvident.
II
The common-law defense of necessity, which heretofore has not been recognized in military law, generally “is available to one who intentionally causes a harm or evil contemplated by an offense, provided that the justifying circumstances result in a lesser net harm or evil as intended by the actor.” Mil-hizer, Necessity and the Military Justice System: A Proposed Special Defense, 121 Mil.L.Rev. 95 (1988) (footnote omitted). As noted by the court below, the common-law defense of necessity “has been recognized in numerous state courts and has gained general acceptance in federal law.” 47 MJ at 549.
In military law, a somewhat narrower defense is provided, under the concept of duress, in RCM 916(h), Manual for Courts-Martial, United States (1998 ed.):1
It is a defense to any offense except killing an innocent person that the accused’s participation in the offense was caused by a reasonable apprehension that the accused or another innocent person would be immediately killed or would immediately suffer serious bodily injury if the accused did not commit the act. The apprehension must reasonably continue throughout the commission of the act. If the accused has any reasonable opportunity to avoid committing the act without subjecting the accused or another innocent person to the harm threatened, this defense shall not apply.
The issue, as framed by appellant, raises a question we left open in United States v. Rankins, 34 MJ 326 (1992): Should the duress defense under RCM 916(h) be limited to cases in which the source of the threat is a third person, or should it also include cases in which the source of the threat involves another physical or natural source? The issue also raises the question whether RCM 916 reflects the appropriate parameters of this type of defense, or whether we should also permit the broader common-law defense of necessity.
As noted by the court below, these questions address some of the most fundamental principles in the military justice system:
[T]he ramifications of an individual choosing to commit an illegal act, in order to avoid what they perceive to be a greater harm, are drastically different in the military than they are in civilian life. In civilian life, innocent individuals may be adversely affected by the commission of the illegal act. In the military, however, the consequences may be much greater. Such a decision affects an individual’s shipmates, the safety and efficiency of the ship, as well as the effectiveness of the mission. Ultimately, the consequences may extend to the severity of the action.
*36747 MJ at 551; accord United States v. Banks, 37 MJ 700, 702 (ACMR 1993) (“[Rejecting the necessity defense goes to the core of discipline within a military organization. In no other segment of our society is it more important to have a single enforceable set of standards.”).
Ill
In an appeal involving a plea of guilty, before we consider whether the existing law of defenses should be interpreted or extended to embrace new principles, the threshold question is whether the accused, after entering the plea, has set forth “matter inconsistent with the plea,” such as a potential defense. See Art. 45(a), UCMJ, 10 USC § 845(a); ROM 910(e), Discussion and (h)(2).2
In the present case, appellant’s unsworn statement during the sentencing proceeding contained a brief speculative comment that at the time he absented himself, he felt that his wife’s “depression might kill her from the stress if [he] went on the UNITAS deployment.” Appellant did not provide any further details indicating an immediate threat of death or serious bodily harm or that there were no alternative sources of assistance for his wife other than his unauthorized absence and missing movement; nor did appellant provide other facts that would establish either the defense of duress under ROM 916(h) or the common-law defense of necessity. See Rankins, 34 MJ at 328-29. Even if we were to hold that the defense of duress could be established through a threat emanating from physical or natural sources, or that the broader common-law defense of necessity should be applicable to courts-martial, appellant’s remarks would be insufficient to render his plea improvident. As we noted in United States v. Faircloth, 45 MJ 172,174 (1996):
We will not overturn a military judge’s acceptance of a guilty plea based on a “mere possibility” of a defense. The record must “show a ‘substantial basis’ in law and fact for” rejecting the plea of guilty. United States v. Prater, 32 MJ 433, 436 (CMA 1991). We also will not “speculate post-trial as to the existence of facts which might invalidate an appellant’s guilty pleas.” United States v. Johnson, 42 MJ 443, 445 (1995).
While the issues raised by appellant are important, we conclude that it would be inappropriate to resolve these questions on the basis of the record before us. These matters could have been raised at trial had appellant contested his guilt on the grounds of necessity. Alternatively, these matters could have been raised through testimony during the providence inquiry or at sentencing, had such testimony included facts providing a substantial basis for addressing the applicability of the necessity defense in the military justice system. Appellant’s vague speculation as to what might have happened had he remained with his shipmates provides an insufficient basis for considering whether the law should be interpreted or extended as he has urged.
IV
The decision of the United States Navy-Marine Corps Court of Criminal Appeals is affirmed.
. This version was in effect at the time of trial.
. See n. 1, supra.