That guarantees preemption.
Schweitzer ’11 [Dan; October; Director and Chief Counsel of the National Association of Attorneys General’s Center for Supreme Court Advocacy; “The Law of Preemption,” National Association of Attorneys General, https://www.naag.org/wp-content/uploads/2020/10/The-Law-of-Preemption-2d-ed.-FINAL.pdf]
The constitution specifically assigns power over foreign commerce to Congress, while power over foreign relations has long been read to be the province of the federal government in the person of the President. Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579, 610-11 (1952) (Frankfurter, J., concurring). in two fairly recent cases, the court has held that the importance of the United States “speaking with one voice” in foreign affairs overrides even traditionally strong state interests, and compels preemption where there is a conflict with federal conduct of foreign relations.
in the first of these cases, Crosby v. National Foreign Trade Council, 530 U.S. 363 (2000), the court found preempted a Massachusetts statute that, as a protest of Burma’s human rights record, forbade the commonwealth from buying goods and services from companies doing business with Burma. even though the state statute governed only Massachusetts’ role as a market participant, the court held that a federal statute imposing certain sanctions on Burma and giving the President authority and latitude to change those sanctions preempted the less-flexible state law. The court ruled that the state law sanctions stood as an obstacle to Congress’ intent to give the President discretion; to congress’ intent “to limit economic pressure against the Burmese Government to a specific range”; and with the President’s capacity “to speak for the nation with one voice in dealing with other governments.” Id. at 377, 381