22 CFR § 127.4 - Authority of U.S. Immigration and Customs Enforcement and U.S. Customs and Border Protection officers.
(a) U.S. Immigration and Customs Enforcement and U.S. Customs and Border Protection officers may take appropriate action to ensure observance of this subchapter as to the export or the attempted export or the temporary import of any defense article or technical data, including the inspection of loading or unloading of any vessel, vehicle, or aircraft. This applies whether the export is authorized by license or by written approval issued under this subchapter or by exemption.
(b) U.S. Immigration and Customs Enforcement and U.S. Customs and Border Protection officers have the authority to investigate, detain or seize any export or attempted export of defense articles or technical data contrary to this subchapter.
(c) Upon the presentation to a U.S. Customs and Border Protection Officer of a license or written approval, or claim of an exemption, authorizing the export of any defense article, the customs officer may require the production of other relevant documents and information relating to the final export. This includes an invoice, order, packing list, shipping document, correspondence, instructions, and the documents otherwise required by the U.S. Customs and Border Protection or U.S. Immigration and Customs Enforcement.
(d) If an exemption under this subchapter is used or claimed to export, transfer, reexport or retransfer, furnish, or obtain a defense article, technical data, or defense service, law enforcement officers may rely upon the authorities noted, additional authority identified in the language of the exemption, and any other lawful means or authorities to investigate such a matter.