A trade agreement signed between more than two sides (typically neighboring or in the same region) is classified as "multilateral". These face the most obstacles- when negotiating substance, and for implementation. The more countries that are involved, the harder it is to reach mutual satisfaction. Once this type of trade agreement is settled on, it becomes a very powerful agreement. The larger the GDP of the signatories, the greater the impact on other global trade relationships. The largest multilateral trade agreement is the North American Free Trade Agreement between the United States, Canada, and Mexico.