Watch Nasty Boys (1989) Official Trailer

When a narcotics team sent to bust some drug dealers are massacred. The police department form a special unit of undercover cops whose identities are withheld from the brass, and are only accountable to the leader, a Lieutenant. While they try to bust the dealers, the Lieutenant tries to find out who gave the dealers the information about the bust. And he suspects that it's someone in the DEA.