KETHLEDGE, Circuit Judge. At issue in this case is whether Congress has plenary power to regulate the conduct of American citizens after they travel overseas. Micky Rife, a Kentucky-born U.S. citizen, travelled to Cambodia and, years later, sexually abused two girls. After returning to Kentucky, he pled guilty to engaging in illicit sexual conduct abroad in violation of 18 U.S.C. § 2423(c). Rife now argues that Congress lacked power to regulate the conduct for which he was convicted. We agree with him that Congress’s power under the Foreign Commerce Clause does not support his conviction. But we also conclude—based on Supreme Court precedent alone—that § 2423(c) as applied here was within Congress’s power to enact legislation implementing treaties. We therefore affirm his conviction.