Washington (CNN) -- The United States has sharply increased efforts to stem the illegal flow of weapons to Mexico, but many problems remain as arms trafficking continues, according to a Justice Department report issued Tuesday.
The 138-page report by Inspector General Glenn Fine is packed with data but lacks specific details on how many weapons find their way across the border to Mexican drug cartels.
According to the report, the Bureau of Alcohol, Tobacco and Firearms and Explosives (ATF) interdicted more than 5,400 firearms and more than 500,000 rounds of ammunition destined for Mexico since Project Gunrunner began in 2006. But officials would not speculate on how many firearms made it to the cartels.
The crackdown in the United States has led to nearly 800 defendants being charged with firearms trafficking to Mexico, the report said. The number of weapons traces (62,600) conducted by Mexico was up nearly sixfold during the past three years, it said.
The report indicated there are major holes in the system, including a lack of ATF resources to fulfill Mexican requests for help.
"For example, ATF has been unable to provide key training and support requested by the government of Mexico," the report found.
U.S. officials stationed in Mexico told investigators there is a lack of coordination among various Mexican law enforcement agencies, and ATF has no single counterpart that it can interact with in coordinating firearms trafficking investigations.
But the inspector general also found a lack of coordination and information sharing among U.S. agencies. The ATF and Immigration and Customs Enforcement have a particularly difficult time coordinating despite a formal memorandum of understanding between the two agencies, the report said.
Fine offered 15 recommendations to the ATF to improve the quality of its investigative leads, to upgrade the sharing of intelligence with other agencies, and to integrate Mexico into its Southwest Border initiatives involving officials in the four border states of Texas, New Mexico, Arizona and California.
In response, the ATF said it concurred with the recommendations.