Critics of the North American Free Trade Agreement (NAFTA) suggest that much of the increase in exports from Mexico to the United States now involves goods that Mexico otherwise would have exported to other nations. Mexican firms choose to export the goods to the United States, the critics argue, solely because the items receive preferential treatment under NAFTA tariff rules. 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.