This is a very important question. There are many thing that law enforcement can do to suppress gangs and drugs. In light of this point, let me make a few suggestions.
First, it is important to examine the causes of drugs and gangs. In other words, when we go to the root of the problem, we are able to solve things on a more important level. When we do this, often drugs and gangs are due to a feeling of hopelessness and alienation. In light of this, community projects, educational programs and other activities that give people hope can help tremendously.
Second, law officials should also seek to prevent these problems even before they start. In other words, there should be education for children on these topics and law officials should give them an alternative way to live. Starting young is much easier than trying to fix problems later on.
Third, law enforcement should also cooperate with other agencies to stop the current drug trade. We need to realize that drugs (and often times gangs) is not a local problem, but a global one. Therefore, cooperation goes a long way.