Well, it turns out that maybe that was just a wee bit over-stated.
In fact, the truth of the matter is almost exactly the reverse: 83% of the weapons seized in Mexico can't be traced back to the U.S:
In 2007-2008, according to ATF Special Agent William Newell, Mexico submitted 11,000 guns to the ATF for tracing. Close to 6,000 were successfully traced -- and of those, 90 percent -- 5,114 to be exact, according to testimony in Congress by William Hoover -- were found to have come from the U.S.
But in those same two years, according to the Mexican government, 29,000 guns were recovered at crime scenes.
In other words, 68 percent of the guns that were recovered were never submitted for tracing. And when you weed out the roughly 6,000 guns that could not be traced from the remaining 32 percent, it means 83 percent of the guns found at crime scenes in Mexico could not be traced to the U.S.
Where ARE they coming from?
-- The Black Market. Mexico is a virtual arms bazaar, with fragmentation grenades from South Korea, AK-47s from China, and shoulder-fired rocket launchers from Spain, Israel and former Soviet bloc manufacturers.
-- Russian crime organizations. Interpol says Russian Mafia groups such as Poldolskaya and Moscow-based Solntsevskaya are actively trafficking drugs and arms in Mexico.
- South America. During the late 1990s, the Revolutionary Armed Forces of Colombia (FARC) established a clandestine arms smuggling and drug trafficking partnership with the Tijuana cartel, according to the Federal Research Division report from the Library of Congress.
-- Asia. According to a 2006 Amnesty International Report, China has provided arms to countries in Asia, Africa and Latin America. Chinese assault weapons and Korean explosives have been recovered in Mexico.
-- The Mexican Army. More than 150,000 soldiers deserted in the last six years, according to Mexican Congressman Robert Badillo. Many took their weapons with them, including the standard issue M-16 assault rifle made in Belgium.
-- Guatemala. U.S. intelligence agencies say traffickers move immigrants, stolen cars, guns and drugs, including most of America's cocaine, along the porous Mexican-Guatemalan border. On March 27, La Hora, a Guatemalan newspaper, reported that police seized 500 grenades and a load of AK-47s on the border. Police say the cache was transported by a Mexican drug cartel operating out of Ixcan, a border town.