From a technical point of view, there is an exception to this principle, since a number of members of the World Trade Organization, which can be considered a large trade agreement, have separate agreements that regulate trade issues concerning a subgroup of WTO members. The North American Free Trade Agreement is an example of such an agreement. It should be noted that most documents that examine different aspects of trade agreements tend to focus on small trade agreements and ignore the WTO, given that most countries are members of the WTO. Unlike environmental agreements, Canada, the United States and Mexico share a single trade agreement, NAFTA. If both sides sign the same trade agreement with other countries, the new NAFTA would replace NAFTA, as would have been the case with the recently abandoned Trans-Pacific Partnership (by the United States). Theoretical research on the development of international environmental agreements: knowledge, critical commentaries and future challenges. International Review of Environmental and Resource Economics,2, 29-67. How many multilateral environmental agreements have been signed? Data or graph of agreements by year and type (contract, protocol, amendment). For example, when signing the North American Free Trade Agreement, Canada, Mexico, and the United States also signed a secondary agreement, the North American Agreement on Environmental Cooperation, which stipulated that each country must enforce its environmental legislation and create a dispute settlement mechanism for enforcement purposes. . .