During his recent summit meeting in Washington with President Obama, Mexican President Felipe Calderon again pressed the United States to tighten its restrictions on firearms. It has become an article of faith in Mexico—and among many pundits in this country—that lax U.S. gun laws are responsible for the carnage perpetrated by the Mexican drug cartels. Calderon has asserted: “If you look carefully, you will notice that the violence in Mexico started to grow a couple of years before I took office in 2006. This coincides, at least, with the lifting of the assault weapons ban in 2004.”

Mexican officials repeatedly insist that 90 percent of the weapons captured from drug gangs originate in the United States. And either explicitly or implicitly, those officials contend that the illicit weapons come from gun shops or gun shows, primarily in the southwestern states. Such allegations oversimplify a complex situation and serve as a scapegoat for the Mexican government’s own failure to stem the tide of killings in that country’s drug wars.

Even the 90 percent figure is highly dubious. Statistics from the Bureau of Alcohol, Tobacco, Firearms, and Explosives cast doubt on the statistic—or anything close to the 90 percent level. For example, the Mexican government submitted 21,726 requests in 2009 to trace weapons that authorities had captured. According to a report issued by the inspector general of the U.S. Justice Department, in only 31 percent of those cases could any source for the firearm, defined as the dealer who originally sold the gun, be identified—much less prove that it was a U.S. dealer.

Moreover, the term “originate” in the United States is both nebulous and misleading. Although some of the weapons the drug cartels use do have their origins in the United States, the sources are not sporting goods stores or gun shows. Many of those weapons come from military depots that the United States government helped fill for friendly Central American regimes during the Cold War. Washington was so concerned about Soviet penetration of that region during the 1980s that it sent shipment after shipment of high-powered weapons to the governments of such countries as El Salvador, Honduras, and Guatemala to use against left-wing insurgents. Records indicate that in addition to rifles, at least 300,000 grenades were sent to the region during the administrations of Ronald Reagan and George H.W. Bush. Many of those grenades found their way to the drug cartels through a lucrative black market. Tighter U.S. firearms laws have no relevance to that problem.

The mythology put forth by the Mexican government may be good propaganda to placate domestic critics, and gun control advocates in the United States eagerly exploit that mythology for their own purposes. But lax gun laws north of the border are not a major factor in the bloody turmoil now afflicting Mexico. Both the Calderon and Obama administrations need to avoid the temptation to find a convenient scapegoat for that tragic situation.