Border Security: CBP Aims to Prevent High-Risk Travelers from Boarding U.S.-Bound Flights, But Needs to Evaluate Program Performance, Report to Congressional Requesters [open pdf - 4MB]
From the highlights section within the document: "DHS seeks to identify and interdict international air travelers who are potential security threats to the United States, such as foreign fighters and potential terrorists, human traffickers, and otherwise inadmissible persons, at the earliest possible point in time. In fiscal year 2015, CBP [Customs and Border Protection] processed more than 104 million U.S.-bound air travelers. CBP operates various predeparture programs domestically and overseas that are designed to identify and interdict high-risk travelers before they board U.S.-bound flights. GAO [Government Accountability Office] was asked to review CBP's predeparture programs. This report addresses (1) how CBP identifies high-risk travelers before they board U.S.-bound flights; (2) the results of CBP's predeparture programs and the extent to which CBP has measures to assess program performance; and (3) how CBP plans to expand its predeparture programs. GAO reviewed CBP policies and procedures and fiscal year 2015 data across these programs. GAO also visited nine foreign and one domestic airport, selected based on location and traveler volume, among other factors. Information from these visits was not generalizable but provided valuable insights into program operations."
Government Accountability Office: http://www.gao.gov/