The 1989 National Defense Authorization Act greatly enhanced the ability of the Department of Defense to expand its detection and monitoring mission in support of drug interdiction. DOD has conducted extensive surveillance of primary smuggling routes by layering ground-, air-, and sea- based radars near the South American countries where cocaine is grown and distributed. As a result, DOD is able to detect suspects early, monitor them continuously, hand them over to law enforcement agencies, and seize large shipments of illegal drugs. However, interdiction has had limited success in deterring smugglers and reducing the flow of cocaine into the United States. Traffickers have adopted new tactics of flying cocaine into Central America and Mexico, from whence it is transported to the U.S. across the border and in shipping containers aboard large vessels. The enormous profits in cocaine trafficking make interdiction losses relatively inconsequential, particularly since production and smuggling costs account for such a small part of street drug prices. The report also contains 2 notes and 1 figure.