In 2017, 47% of illegal immigrants in the United States originate from Mexico. The United States has built a barrier on much of its border with Mexico. In recent years, the majority crossing from Mexico into the United States have been from Central America. Illegal trade of weapons The US is the largest source of illicit traffic of weapons to Mexico. Many of the traceable weapons come from American weapons markets and festivals that do not have regulations for the buyers, and there is a geographic coincidence between the supposed American origin of the firearms and the places where these weapons are seized: mainly in the Northern Mexican states. Firearms that make their way to Mexico come from the American civilian market. However grenades are also smuggled from the US to Mexico. In an effort to control smuggling of firearms, the U.S. government is assisting Mexico with technology, equipment and training. Project Gunrunner was one such efforts between the U.S. and Mexico to collaborate in tracing Mexican guns which were manufactured in or imported legally to the U.S. In 2015, Official reports of the U.S. government and the Bureau of Alcohol, Tobacco, Firearms and explosives (ATF) revealed that Mexican cartels improved their firearm power over that last years, and that 70% of their weapons come from the U.S. ATF gunwalking scandal The American ATF's Project Gunrunner has as its stated purpose the stoppage of the selling and exportation of guns from the United States into Mexico, with the goal of denying Mexican drug cartels the firearms considered "tools of the trade". However, in February 2011, it brought about a scandal when the project was accused of accomplishing the opposite by ATF permitting and facilitating "straw purchase" firearm sales to traffickers, and allowing the guns to "walk" and be transported to Mexico. Several of the guns sold under the Project Gunrunner were recovered from crime scenes in Arizona, and at crime scenes throughout Mexico. Obama administration Mexico was not high on the priorities of the Obama Administration, but slow progress was made on security issues. As of 2013, Mexican students formed the 9th largest group of international students studying in the United States, representing 1.7% of all foreigners pursuing higher education in the U.S. Trump administration The four-year term of President Donald Trump, who had provoked the ire of the Mexican government through threats against companies who invest in Mexico instead