The GAO report has been corroborated through other sources. William Newell, Special Agent in Charge of ATF's Phoenix Field Division, testified before a U.S. House of Representatives subcommittee in March 2009, stating, "Drug traffickers are able to obtain firearms and ammunition more easily in the U.S., including sources in the secondary market such as gun shows and flea markets. Depending on State law, the private sale of firearms at those venues often does not require record keeping or background checks prior to the sale." The ATF has also reported that, "Trends indicate the firearms illegally crossing the U.S.-Mexico border are becoming more powerful. ATF has analyzed firearms seizures in Mexico from FY 2005–07 and identified the following weapons most commonly used by drug traffickers: 9mm pistols; .38 Super pistols; 5.7mm pistols; .45-caliber pistols; AR-15 type rifles; and AK-47 type rifles." However, this is based only on the weapons sent to the ATF to be traced, a small portion of all firearms seized by the Mexican government, and the extent to which they are representative of all seized firearms is disputed. According to Raul Benitez, a security expert at the National Autonomous University of Mexico, "Mexico's southern border with Guatemala has long been an entry point for such weapons and today could account for 10 to 15 percent coming through." William La Jeunesse and Maxim Lott have described Mexico as a "virtual arms bazaar," where one can purchase a wide variety of military weapons from international sources: "fragmentation grenades from South Korea, AK-47s from China, and shoulder-fired rocket launchers from Spain, Israel and former Soviet bloc manufacturers." In addition, they say that Mexican drug cartels have long-established drug- and gun-running ties with Latin American revolutionary movements such as Colombia's FARC. Further, China has supplied military arms to Latin America and Chinese-made assault weapons have been recovered in Mexico, according to Amnesty International. Finally, the Mexican army has seen rampant desertion rates (150,000 in the last six years) and many soldiers have taken their weapons home with them, including Belgian-made M16s.