Some critics of the North American Free Trade Agreement (NAFTA) suggest that firms outside NAFTA nations sometimes shift unassembled inputs to Mexico, assemble the inputs into final goods there, and then export the final product to the United States in order to take advantage of Mexican trade preferences. What term describes what these critics are claiming is occurring with regard to U.S.-Mexican trade as a result of NAFTA? Explain your reasoning. (See page719 of the textbook.)