Efforts to stave gun smuggling into the United States has failed, and the US federal watchdog agency has ultimately blamed officials from both Mexico and the United States for these botched efforts.

According to a draft report obtained from The Guardian, the Government Accountability Office (GAO) criticized US law enforcement agencies and Mexican authorities for not cooperating in fighting against Mexico's notorious drug cartels. They said that lack of cooperation of both parties was to blame for the failed efforts to stop gun smuggling.

Mexico restricts gun sales, but the gun smuggling of US weapons has fueled battles between Mexican drug gangs and security forces. These violent clashes between both parties have killed more than 100,000 people since 2007.

Experts say that operations to stop the gun smuggling have seen little success. US agents have reportedly lost track of guns allowed to enter Mexico between 2009 and 2011.

Mexican President Peña Nieto has since then reestablished cooperation with US authorities after taking office in late 2012. The US-Mexican ties, long undermined by mutual distrust since Nieto's predecessor, Felipe Calderón's reign, has improved.

The report said that the teamwork between the two countries has improved since 2015, but also said that there are issues on corruption among Mexican authorities. Peña Nieto has since replaced his attorney general last year with an official who is more open to cooperating with the US government.

New York Times said that nearly 105,000 guns were reported to have been seized in Mexico and submitted for tracing from 2009 to 2014. 70% came from the United States, as per a report from the US Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). Another 17% of these seized firearms were linked to other countries, while 13% could not be traced, possibly due to the failure of US gun shops that closed down to turn over records.

US Immigration and Customs Enforcement (ICE) and ATF also failed to ensure cooperation amongst their agents on trafficking investigations.

The GAO said it found deficiencies in information-sharing between ATF and ICE. There was also confusion about their roles, even after they were urged to improve teamwork.

Mexican lawmakers claimed that lax gun laws in the US is the chief reason why gun traffickers buy and move guns. They also blamed corruption among Mexico's customs agents.

"The fight against arms trafficking has been a failure," said Raul Benítez, a security expert at the National Autonomous University in Mexico.