The U.S. Department of Justice has found that federal agents lacked proper guidance and experience when they conducted undercover sting operations in several cities since 2010 that were aimed at disrupting illegal gun sales.

The Justice Department's inspector general's office released a report Thursday examining shortcomings with U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives' storefront sting operations in Milwaukee; Pensacola, Florida; St. Louis; Wichita, Kansas; and Boston.

The report found that agents who worked the operations lacked policies, experience and supervision. It also noted the operations have to do a better job defining the problem they're trying to solve.

Problems with the ATF's storefront operations surfaced in 2013 after the Milwaukee Journal Sentinel published an investigation detailing multiple problems with the operation in that city.