sentences:  Illegal immigration and illegal trade in drugs and in firearms have been causes of differences between the two governments, but also of cooperation.While condemning the terrorist attacks of 9/11 and providing considerable relief aid to the U.S. after Hurricane Katrina, the Mexican government, pursuing neutrality in international affairs, opted not to actively join the controversial War on Terror and the even more controversial Iraq War, instead being the first nation in history to formally and voluntarily leave the Inter-American Treaty of Reciprocal Assistance in 2002, though Mexico later joined the U.S. in supporting military intervention in the Libyan Civil War.According to a 2010 Gallup poll, 4.4% of surveyed Mexicans, roughly 6.2 million people, say that they would move permanently to the United States if given the chance, and according to the 2012 U.S.