Some researchers have asserted that most weapons and arms trafficked into Mexico come from gun dealers in the United States. There is strong evidence for this conclusion, indicating that many of the traceable weapons come from the failed American government Operation "Fast and Furious", 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. Most grenades and rocket-launchers are smuggled through Guatemalan borders from Central America. However some grenades are also smuggled from the US to Mexico or stolen from the Mexican military. United States Department of Homeland Security (DHS) officials have stated that the statistic is misleading: out of approximately 30,000 weapons seized in drug cases in Mexico in 2004–2008, 7,200 appeared to be of U.S. origin, approximately 4,000 were found in ATF manufacturer and importer records, and 87 percent of those—3,480—originated in the United States.