"Since fiscal year 2000, the availability of U.S. and allied assets spent on interdiction operations in the transit zone [South America through the Caribbean Sea and eastern Pacific Ocean] — as measured in on-station ship days and flight hours -— has varied. U.S. and allied on-station ship days decreased from approximately 3,600 days in fiscal year 2000 to about 3,300 in fiscal year 2005, and U.S. and allied on-station flight hours increased from approximately 10,500 hours in fiscal year 2000 to almost 12,900 in fiscal year 2005. However, on-station ship days peaked in fiscal year 2001 and flight hours peaked in fiscal year 2002, but both have generally declined since then, primarily because Defense has provided fewer assets. Declines in Defense assets were largely offset by the Coast Guard, CBP US Bureau for Customs and Border Protection), and several allied European nations -— France, the Netherlands, and the United Kingdom. Nevertheless, with the assets available in recent years, JIATF-South (Joint Interagency Task Force-South) reports that it detected (made visual contact with) less than one-third of the known maritime drug movements."

Source

"Drug Control: Agencies Need to Plan for Likely Decline in Drug Interdiction Assets, and Develop Better Performance Measures for Transit Zone Operations," Government Accountability Office (Washington, DC: USGAO, Nov. 2005), GAO-06-200, p. 4.
http://www.gao.gov/new.items/…