Opinion of the Court
EVERETT, Chief Judge:Appellant was tried by a general court-martial composed of a military judge alone at Camp Casey, Republic of Korea, in Feb*285ruary 1984. Contrary to his pleas, he was found guilty of attempted consensual sodomy and of rape, in violation of Articles 80 and 120, Uniform Code of Military Justice, 10 U.S.C. §§ 880 and 920, respectively. He was sentenced to a dishonorable discharge, confinement for 10 years, total forfeitures, and reduction to pay grade E-l. The convening authority approved this sentence except for confinement exceeding 42 months. The Court of Military Review affirmed in a short-form opinion.
This Court granted review of these three issues raised by appellate defense counsel:
I
WHETHER THE REFUSAL OF THE MILITARY JUDGE TO ALLOW DEFENSE COUNSEL TO CROSS-EXAMINE THE PROSECUTRIX AND PRESENT EVIDENCE ABOUT THE PROSECUTRIX’S SEXUAL BEHAVIOR WITH THE COACCUSED GREER AND ANOTHER SOLDIER VIOLATED THE SIXTH AMENDMENT’S CONFRONTATION CLAUSE.
II
WHETHER THE MILITARY JUDGE ERRED TO THE SUBSTANTIAL PREJUDICE OF APPELLANT BY PERMITTING CROSS-EXAMINATION INTO AN OFFER BY APPELLANT TO COMPROMISE MS. HAN’S CLAIM TO AVOID KOREAN CRIMINAL AND CIVIL ACTION AND BY ADMITTING THE SUBSEQUENT WRITTEN AGREEMENT INTO EVIDENCE.
III
WHETHER THE MILITARY JUDGE ABUSED HIS DISCRETION BY FAILING TO ADMIT INTO EVIDENCE THE RESULTS OF APPELLANT’S POLYGRAPH EXAMINATION.
Oral argument was ordered only on the first two issues.
I
The military judge found appellant guilty of rape and attempted sodomy of Mrs. Han on the night of October 24, 1983. Mrs. Han, a deaf-mute Korean, sold flowers in bars to American servicemembers. Appellant, Specialist Four Greer, and Sergeant Williams were American servicemembers who were at the Drink Store Club, a bar outside Camp Casey, on the night in question. It was established at trial that Mrs. Han entered this bar and attempted to sell flowers and, failing to do so, left. The circumstances surrounding her departure were highly disputed.
Mrs. Han testified for the prosecution in this case through an interpreter of sign language and one of Korean. She testified that after leaving the bar alone, she was grabbed and dragged into an alley by five assailants. Four of them had sexual intercourse with her against her will by using force. The fifth attempted to force her to commit oral sodomy on him. She could not identify these assailants except to note that four were black and one white.
A pretrial statement by Jensen, a white male, was admitted against him as part of the Government’s case. According to this document, he, Greer, and Williams had been drinking heavily that night at various bars, the last of which was the Skoosh (Drink) Store. Jensen and Greer left the Skoosh (Drink) Store and encountered Williams and a Korean girl in an alley. Williams or Greer grabbed her and took her into a smaller alley. Greer went into this alley with the girl, while Jensen and Williams waited in the bigger alley. Jensen looked into the alley and saw Greer and the girl engaging in sexual intercourse. When Greer came out of the alley, Jensen entered, attempted to have sexual intercourse with her, and achieved partial, but not full, penetration. The Korean girl “looked confused” and never indicated her willingness; but she did not resist, except when he attempted to have her perform oral sodomy on him. Moreover, she held his “penis in her hand and was guiding it.” *286Finally, he rejoined Greer, left Williams at the scene, and returned to his barracks.
Other government evidence was admitted concerning this incident and Mrs. Han’s subsequent conduct in reporting this matter to the military police. In addition, physical evidence and medical testimony were received.
In his defense, Jensen testified that he had been drinking with Greer, Williams, a man named Palmer, and an unidentified Puerto Rican at the Drink Store late at night on October 24, 1983. Appellant first noticed Mrs. Han when she was walking out of the door with his barracks friend, Greer. He put on his coat and followed them into the street where he observed them walking with “their arms around each other’s waist.” He followed them through a big alley and eventually he observed them enter a smaller alley. He looked in the alley and saw them “making love”; and no force was apparent.
Appellant testified that he “[sjmoked a cigarette” until Greer came out of the small alley. Jensen then entered the alley, at which time he observed “Sergeant Williams coming up the bigger alley.” Mrs. Han “was laying on her back.” According to Jensen:
She had her legs spread apart, sir, and I knelt down in between them. I took my penis out from my fly, sir, and when I leaned down to get on top of her, she took my penis in her hand and started fondling it and rubbing it on her pubic hair, sir. My penis only got about — not even semi-erect, just sort of erect.
After testifying that he did not remember if he actually penetrated her, Jensen said:
When I gave up trying to make penetration, sir, I sit up and got along side of her and I asked her to give me a blow job, and she looked at me like she didn’t understand. So I put my hand on her shoulder, sir, and guided her head towards my penis. As soon as my penis was about a foot — foot and a half away from my — as soon as her head was about a foot and a half from my penis she waived her hands like this and shook her head (the witness crossed his hands in front of his face, crossing at the area of the wrist) and I didn’t want to make her do anything she didn’t want to. So that’s when Specialist Greer come by and said, “Jensen, we’ve got to go.” So that’s when I left Ms. Han in the alley, sir.
On cross-examination, Jensen admitted that he had never seen Mrs. Han before.
Specialist Greer testified that he had left the bar with Mrs. Han and proceeded to the small alley, where he engaged in consensual sexual intercourse with her. He then left her and observed Jensen enter the small alley. Greer had no conversation with appellant; but later he reentered the alley to tell appellant that they should go back to the barracks.
II
In prosecutions for nonconsensual sexual offenses, Mil.R.Evid. 412, Manual for Courts-Martial, United States, 1969 (Revised edition), excluded “evidence of a victim’s ... past sexual behavior with persons other than the accused,” unless “offered ... upon the issue of whether the accused was ... the source of semen or injury” or unless “constitutionally required to be admitted.” Relevance is the key to determining when the evidence is “constitutionally required to be admitted.” United States v. Dorsey, 16 M.J. 1, 5 (C.M.A.1983); see United States v. Colon-Angueira, 16 M.J. 20, 30 (C.M.A.1983) (Everett, C.J., concurring). Generally, past sexual behavior with third persons is not relevant to the issues of the case. However, sometimes it may be, even though the issue does not concern “the source of semen or injury.” Cf. United States v. Dorsey, supra.
In the present case, the Government claimed that Mrs. Han had first been raped in an alley by Specialist Greer, immediately thereafter raped by appellant, and finally raped by Sergeant Williams. Greer and appellant both testified that shortly before the alleged rapes, Mrs. Han danced with *287Greer in a bar, where they were present along with other soldiers. While they were in the store, she grabbed Greer’s penis; and, pursuant to this implied invitation, he and she walked out together, went to a nearby alley, and engaged in voluntary sexual intercourse.
According to Jensen, immediately thereafter he had attempted to have intercourse with Mrs. Han; but, despite her cooperation and encouragement, he failed because his drunkenness prevented him from having an erection and penetrating her vagina. Then, when she refused to engage in fellatio with him, he departed.
In connection with appellant’s defense that the alleged victim consented to sexual intercourse, he was entitled to offer evidence that on two previous occasions, Mrs. Han had engaged in voluntary intercourse with Specialist Greer and with another soldier. As we interpret Mil.R.Evid. 412, it does not exclude such evidence.
Mil.R.Evid. 412(b)(2)(B) provides that “past sexual behavior with the accused” may be admitted in evidence when offered to show consent by the alleged victim. Presumably, the rationale is that a past sexual relationship with the accused tends to corroborate his defense that the victim also consented on the occasion which has given rise to prosecution.
If this be so, parallel reasoning would suggest that Mrs. Han’s consent to intercourse with Greer on prior occasions tends to corroborate Greer’s testimony at appellant’s trial that she consented on this particular occasion, as well. In this event, the evidence of prior consent was very material to disprove the prosecution theory that Mrs. Han had initially been raped by Greer, then immediately thereafter by Jensen, and finally by Williams. The situation is very akin to that present in United States v. Dorsey, supra, where, because of the special circumstances, the alleged rape victim’s prior intercourse with another person was material to the theory of defense.
Although the excluded evidence would chiefly be important as to Jensen’s claim that Mrs. Han, at least initially, was willing to have intercourse with him, it also tends to support the defense theory that appellant reasonably believed she was willing to do so. Cf. United States v. Carr, 18 M.J. 297 (C.M.A.1984). If Mrs. Han consented to intercourse with Greer and then immediately thereafter was lying on her back in the alley with her legs widespread when appellant approached, there is corroboration as to his state of mind. Accordingly, for this reason as well, the defense proffer of this evidence was adequate; and the evidence should have been admitted.
Ill
During the Government’s presentation of its case, trial counsel attempted to offer evidence of an agreement prepared in the Korean language but signed and executed by Greer, Jensen, and Williams. Pursuant thereto, they had paid $780 to Mrs. Han in return for her agreement that “I will not make a complaint against the assailants by civil or criminal law.” When the agreement was first offered, the military judge refused to admit it in evidence. However, subsequently he permitted Greer to be cross-examined about it, and then he allowed the agreement to be received in evidence.
Appellate defense counsel contend that under Mil.R.Evid. 408 — which renders inadmissible evidence of compromises and offers of compromise — the agreement should have been excluded and also that under Mil.R.Evid. 403, its probative value, if any, was far outweighed by its prejudicial effect. Contrariwise, appellate government counsel insist that efforts to buy out a criminal prosecution do not fall within the exclusion in Mil.R.Evid. 408. Moreover, they urge that the agreement with Mrs. Han to purchase her silence was not an offer of settlement but an attempt to obstruct justice and prevent prosecution and therefore was material in showing appellant’s consciousness of guilt.
The military judge made much ado about the breadth of the agreement’s language. In his view, the reference to “a *288complaint against the assailants by civil or criminal law” would even include a complaint to American military authorities that might result in a court-martial. Moreover, he could not perceive any public policy that favored inclusion of such agreements within the scope of Mil.R.Evid. 408. In both respects, he erred.
The context of the agreement was made clear when, during direct examination of appellant, he was asked about signing the agreement and replied:
A. The way it was explained to me, sir, is that — Sergeant Williams told me a Korean contacted his wife saying that Ms. Han wanted $2,500.00 to drop the charges. I said, “I am not going to pay that much.” And through negotiations between whoever and Mrs. Williams, the amount got dropped down to $800.00. That’s when I came and asked you if I should pay it or not.
Q. And — okay, you basically — you were going to be prosecuted in a Korean court unless you paid, that was your understanding, right?
A. That’s what you told me, sir.
Q. And what was the advice that I gave you?
A. You told me to pay my share of the money because it would get tossed out of Korean courts and you cannot represent me fairly enough in a Korean court. And if I got — things took [a] turn for the worse and I got convicted, I would not want to spend time in the Korean jail, sir.
The agreement was prepared in Korean and addressed to a Korean official — the Superintendent, Uijongbu Police Station. From all indications, it was not intended for American military authorities. Contrary to the military judge’s view, then, it clearly only contemplated forestalling criminal and civil proceedings in Korean courts and was not directed to prosecution by court-martial.
It is both legal and customary in some Far Eastern and other countries for an accused to make monetary restitution to victims of alleged crimes as a means of avoiding both civil action and criminal prosecution. Undoubtedly, this practice is sometimes followed by American service-members overseas in order to avoid problems with local courts. Moreover, we are sure that this practice is well known to American military authorities — and probably is often encouraged by them. It even is likely that, on occasion, official funds have been advanced to pay alleged foreign victims and thereby extricate American servicemembers from imbroglios in the local courts. Moreover, we doubt that anyone would suggest that appellant’s military defense counsel was engaged in obstructing justice by advising Jensen to go ahead with the agreement.
In such instances, the purpose is not sinister. Instead, the desire is to protect American servicemembers from trial in an unfamiliar legal system, where they will understand neither the language nor the procedure. No similar incentive exists with respect to paying a victim not to cooperate with prosecutors in a court-martial or in any American civil court.
Perhaps the military judge had forgotten that American national policy — expressed in a congressional reservation when the NATO Status of Forces Agreement was ratified — is that, insofar as practicable, our military personnel should be tried by courts-martial rather than by courts of a host country. See United States v. Jordan, 1 M.J. 334, 336 n. 2 (C.M.A.1976). With this in mind, American military authorities have consistently attempted to obtain waivers of foreign jurisdiction to try servicemembers.
To accept the Government’s contention would create a future pitfall for American servicemembers stationed overseas. If under similar circumstances they decline to execute agreements of this type, they would be subject to criminal prosecutions in the local courts which otherwise could be avoided. If, however, they make such payments or enter into agreements like the one in the present case, they would risk the *289later use of that agreement as evidence against them in a court-martial.
In this case, the agreement had no relevance, and its reception in evidence had a prejudicial effect. We cannot assume that the military judge disregarded the agreement in his role as a factfinder, since apparently he proceeded on the erroneous premise that it indicated a consciousness of guilt on Jensen’s part.
IV
We have concluded that the military judge’s exclusion of the exculpatory polygraph evidence was within his discretion in light of the factors discussed in United States v. Gipson, 24 M.J. 246 (C.M.A.1987). Of course, this is not to say that he would have erred by admitting this evidence.
V
In light of the military judge’s error in excluding defense evidence that should have been admitted under Mil.R.Evid. 412 and admitting evidence that should have been excluded pursuant to Mil.R.Evid. 408 and 403, appellant was prejudiced. The evidence of guilt was not overwhelming, and there was some strong defense evidence. Indeed, it is noted that Specialist Four Greer was subsequently acquitted when he was tried by a court-martial with members. Cf. Standefer v. United States, 447 U.S. 10, 100 S.Ct. 1999, 64 L.Ed.2d 689 (1980).
VI
The decision of the United States Army Court of Military Review is reversed; the findings of guilty and the sentence are set aside. The record of trial is returned to the Judge Advocate General of the Army. A rehearing may be ordered.