The first phase of the work was performed between May 1995 and February 1996 and included meetings and interviews with representatives of 17 Federal departments and agencies, an analysis of relevant documentation and studies, and site visits to observe the technologies being used to detect explosives or narcotics. Findings show that the intelligence community believes that the threat of terrorism within the United States has increased. Although no specific aviation threat is known, experts believe that aviation is likely to remain an attractive target for terrorists. Narcotics trafficking is a continuing concern. Although cocaine has been the primary threat since 1985, heroin is becoming more of a threat. To counter these threats, the Federal Aviation Administration (FAA) and Customs have developed strategies that rely on intelligence information; various procedures, such as profiling and targeting high-risk shipments for examination; and technologies. The FAA relies on a strategy of "tailored response" to mandate security procedures commensurate with the level of threat at specific places and times. Customs' strategy includes disseminating intelligence on drug trafficking, targeting high-threat conveyances and cargoes, and using detection technologies; the current emphasis is on the Southwest border, particularly on trucks, private vehicles, and their contents. Concealed explosives and narcotics are difficult to detect with the use of technologies currently deployed in the United States. The FAA has certified an advanced automated explosive detection system, but has not required deployment of that system. The FAA's preliminary estimates are that the cost of purchasing and installing the system at the 75 busiest domestic airports could range from $400 million to $2.2 billion, depending on the mix of technologies and procedures. Customs has one truck X-ray system at the Southwest border for detecting narcotics and plans to acquire others at a cost of approximately $38 million. Its plans for seaports and the use of mobile systems have not been clearly defined. Other countries, such as the United Kingdom and France, are already deploying advanced technologies intended for explosive or narcotics detection.