OPINION

Defendant-Appellant Keith O. Newman (“Newman”) appeals his sentence after the United States Government (“government”) failed to file a motion for a substantial-assistance downward departure pursuant to § 5K1.1 of the United States Sentencing Guidelines (“USSG”). Newman pleaded guilty to five counts of weapons and methamphetamine possession and distribution in an agreement under which the government retained sole discretion to decide whether Newman rendered substantial assistance in the investigation and prosecution of other suspects. The government declined to move for a downward departure, the district court denied any downward departure, and we now AFFIRM the district court’s judgment.

I. FACTS AND PROCEDURE

Newman’s fortunes had only just begun to take a turn for the worse on May 24, 2000, when police officers in Dunlap, Tennessee arrested him on an outstanding domestic violence warrant and discovered seven grams of methamphetamine, $2,920 in currency, and a loaded pistol in his car. Over the ensuing year, several different law enforcement agencies discovered Newman in possession of methamphetamine, weapons, and materials used in the manufacture of methamphetamine on three separate occasions in two states. Newman was charged with several drug and gun-related federal offenses in a criminal complaint filed with the Eastern District of Tennessee on May 8, 2001. A grand jury returned a five-count indictment against Newman on May 22, 2001.1 Newman entered into a written agreement with the government on July 19, 2001, under which he pleaded guilty to Counts One and Three of the Indictment and the government agreed to not prosecute on the remaining three counts. In paragraph 4(b) of the plea agreement, Newman and the government agreed:

*490If, in the view of the United States, Mr. Newman renders substantial assistance to the United States, at the time of sentencing the United States will recommend to the Court that he receive a downward departure from the sentencing guidelines range pursuant to Section 5K1.1 of the Federal Sentencing Guidelines and below any mandatory minimum pursuant to 18 U.S.C. § 3553(e). The determination as to whether or not Mr. Newman has rendered substantial assistance will be made solely by the United States.

Joint Appendix (“J.A.”) at 19-20. The agreement also stated that, “if the defendant violates any federal, state or local law after entering into this plea agreement, then the United States will be relieved from any obligation it may have under the plea agreement, including the obligation to file a motion for a downward departure.” J.A. at 20.

Newman argues that between the district court’s acceptance of the plea agreement and the sentencing hearing on December 7, 2001, he substantially assisted the government, contributing to the prosecution and conviction of “numerous individuals.” Appellant’s Br. at 8. The government counters that Newman’s assistance was limited to attendance at a “proffer session,” at which Newman provided the government with previously known information about other methamphetamine manufacturers. Appellee’s Br. at 9, 18. At the sentencing hearing, the government agreed that Newman “did in fact cooperate with the government,” and “gave some information that was. valuable,” J.A. at 44-45, but it claimed that while in jail awaiting sentencing, Newman agreed to sell another inmate several firearms and discussed a potential sale of plastic explosives, which prevented the government from using Newman’s testimony at the trial of another suspect because it destroyed his credibility as a witness. The government asserted that while it was denying Newman “the chance to get a reduction for substantial assistance, ... [Newman] denied the government the benefit of his cooperation ... because we didn’t want to use him because of the fact that he was engaged in this— what we believe to be further criminal activity.” J.A. at 45.

In response to the government’s apparent unwillingness to file a § 5K1.1 motion, Newman’s attorney moved the court to consider a downward departure under § 5K2.0 because Newman’s “substantial assistance” was a mitigating factor. Newman’s attorney claimed that it was unconstitutional for the government to neglect to file the § 5K1.1 motion because of Newman’s alleged misconduct if Newman did in fact render substantial assistance. The government then sought to put ATF Agent Gillette on the witness stand to testify as to Newman’s involvement in the alleged gun sale, but the court declined to receive the witness, instead ruling that the government did not act improperly in exercising its discretion not to move for a downward departure. The district court sentenced Newman to serve a term of 157 months’ incarceration,2 recommended that Newman receive 500 hours of substance abuse treat*491ment, and ordered Newman to pay restitution. The district court had jurisdiction over the indictment pursuant to 18 U.S.C. § 3231, and we have jurisdiction over the final sentencing decision of the district court pursuant to 28 U.S.C. § 1291.

II. ANALYSIS

A. Standard of Review

We review plea agreements as if they were contracts and employ traditional principles of contract law. United States v. Lukse, 286 F.3d 906, 909 (6th Cir. 2002). Factual findings are reviewed for clear error, id., but neither party here contests the language of the plea agreement. The district court’s determination of whether the government’s conduct violated the plea agreement is a question of law that we review de novo. United States v. Wells, 211 F.3d 988, 995 (6th Cir. 2000).

Initially, we note the strange footing of this appeal, because at sentencing Newman neither directly challenged the government’s failure to file a § 5K1.1 motion nor filed his own motion to compel the government to move for a downward departure. Newman instead moved under § 5K2.0 for a downward departure and argued that “it would be improper and therefore unconstitutional for the government to then breach its agreement” if in fact the defendant rendered substantial assistance. J.A. at 48. The failure to file a motion to compel raises the specter of a waiver. However, because counsel did argue that the government unconstitutionality breached the agreement, albeit in the context of a § 5K2.0 motion, the issue is properly before this court. See United States v. Benjamin, 138 F.3d 1069, 1074 (6th Cir. 1998) (considering § 5K1.1 claim. even though defendant “never formally objected to the government’s refusal to make a § 5K1.1 motion”).3 Newman does not appeal the denial of the § 5K2.0 motion, and thus we only review the district court’s holding that impermissible motives did not spur the government to refrain from acting under § 5K1.1.

B. Whether the Government Breached the Plea Agreement

The central issue on appeal is whether the government breached the plea agreement by failing to file a § 5K1.1 motion. As provided by 18 U.S.C. § 3553(e), district courts, “[u]pon motion of the Government,” can impose a sentence below the statutory minimum when a defendant has rendered “substantial assistance in the investigation or prosecution of another person who has committed an offense.” 18 U.S.C. § 3553(e) (emphasis added). USSG § 5K1.1 mirrors the statutory provision, permitting a district court to reduce a sentence “[u]pon motion of the government stating that the defendant has provided substantial assistance in the investigation or prosecution of another person who has committed an offense____” USSG § 5K1.1. There is inherently a large degree of government discretion in deciding whether to file a substantial assistance motion and “[sjubstantial weight should be given to the government’s evaluation of the extent of the defendant’s assistance, particularly where the extent and value of the assistance are difficult to ascertain.” USSG § 5K1.1, Application Note 3.

However, the government’s decision to decline to file a motion is not entirely insulated from attack. When the govern*492ment flatly promises in the plea agreement to make a substantial assistance motion, bargaining away its discretion, “[t]he government then is obligated to make the motion” unless the government can prove by a preponderance of the evidence that the defendant breached the plea agreement. Benjamin, 138 F.3d at 1074. When the government retains its discretion, the district court’s review of a decision not to file is extremely circumscribed, as “a district court may only review the government’s refusal to make the motion to determine whether the refusal is based on unconstitutional considerations, such as the defendant’s race.” Id. at 1073; see also Wade v. United States, 504 U.S. 181, 186, 112 S.Ct. 1840, 118 L.Ed.2d 524 (1992) (recognizing that federal district courts have the authority to grant a remedy if the refusal to file a substantial assistance motion was based on an unconstitutional motive); United States v. Igbinovia, No. 01-5878, 2003 WL 21771951, at *3, 71 Fed. Appx. 472 (6th Cir. July 22, 2003). Even if the government acts in bad faith when it refuses to file a substantial assistance motion, the court cannot overturn the government’s decision absent some evidence of unconstitutional motives. United States v. Moore, 225 F.3d 637, 641 (6th Cir. 2000).

Recently, we decided United States v. Lukse, 286 F.3d 906 (6th Cir. 2002), which Newman relies upon heavily as mandating an outcome in his favor. In Lukse, two defendants signed a plea agreement that reserved sole discretion to the government. Id. at 908. It was undisputed that both defendants provided the government “with some assistance”; they gave the government previously unknown information that led to the investigation, arrest, and indictment of several other individuals. Id. at 909. Before the sentencing hearing, the defendants were observed smoking marijuana in jail and, as a result, the government informed the defendants that it would not file downward departure motions because the defendants had lost their credibility as trial witnesses. Id. The defendants moved the district court to compel the government to file substantial assistance motions, but the district court refused, reasoning that there was no evidence that the government acted upon unconstitutional motives. Id.

We reversed and remanded because the government failed to discuss the defendants’ role in the investigation, as opposed to the prosecution, of others during the sentencing hearing. Both the plea agreement in Lukse and the language of § 5K1.1 imply that failing to render substantial assistance in the prosecution of other suspects does not automatically negate the ability to render substantial assistance in the investigation of other suspects. Lukse established that the government must discuss both categories of assistance in explaining its decision not to file a downward departure motion. We stated:

The government’s insistence ... that the sole reason for the motion not being filed was the [defendants’] damaged trial credibility ... shows that the government only determined whether the [defendants] had substantially assisted them during the prosecution of other suspects ... [and] they never refused to file the motion because substantial assistance had not been rendered during the investigation of other suspects.

Id. at 911. Absent an on-the-record statement that the defendants did not provide substantial investigative assistance, the government has “no proof that [the government] in fact decided that the [defendants] did not provide substantial assistance during the investigation of other suspects.” Id. at 912. Thus, the government must “analyze and determine whether substantial assistance had been ren*493dered.” Id. It cannot “leave the question unanswered” regarding either type of assistance; it cannot fail to make a motion because it “never made any decision as to whether substantial assistance was rendered.” Id. Lukse places the burden upon the government to show that a defendant failed to provide substantial assistance in both the investigation and the prosecution of other suspects, because “[a]bsent this proof, the government was bound by the plea agreement and [is] required to file [a] downward departure motion[].” Id. at 914.

Based upon Lukse, we first assess whether the government denied that Newman rendered substantial assistance in both the investigation and prosecution of others. The government clearly stated that Newman failed to provide substantial prosecutorial assistance because his alleged criminal activity undermined his usefulness as a witness. In relation to the investigation of others, the government stated that Newman “did in fact cooperate with the government” and “gave some information that was valuable,” J.A. at 44-45,4 but it did not label such help as “substantial assistance.” In contrast to Lukse, the government did not completely fail to discuss Newman’s investigative assistance. While the government should have been much clearer in enunciating its determination that Newman did not render substantial investigative assistance, we cannot assume that the use of the terms “cooperate” and “valuable” in lieu of “substantial assistance” was unintentional. “The difference between substantial assistance and full cooperation is not merely semantic. A defendant might fully cooperate with the government yet fail to provide information that substantially assists it.” United States v. Wells, 211 F.3d 988, 996 (6th Cir. 2000); see also United States v. Houston, No. 01-3512, 2002 WL 1455330, at *2, 40 Fed.Appx. 139 (6th Cir. July 2, 2002) (highlighting the critical distinction between a plea agreement that speaks in terms of “cooperation” versus one that employs the phrase “substantial assistance”). Furthermore, whereas the government’s silence in Lukse was all the more deafening when juxtaposed with several statements made by state and federal law enforcement officers attesting to the defendants’ assistance, the government’s statement that Newman merely “cooperated” was not belied by any evidence to the contrary. The government’s mention of Newman’s cooperation without an accompanying discussion of substantial assistance suffices, although barely, as an exercise of the government’s discretion not to file a downward departure motion. Because the government did deny that Newman rendered substantial assistance, we are limited to reviewing the government’s decision for unconstitutional motives, of which Newman presents no evidence.

III. CONCLUSION

Because the government explicitly claimed before the district court that Newman did not substantially assist the government in the prosecution of other suspects, and because the government more obliquely asserted that Newman failed to *494render substantial investigative assistance, we AFFIRM the judgment.