Note: The number in parenthesis following each quote references its respective source below.

Brief Chronology of Military Involvement in US Drug Law Enforcement and Drug Control Policy, and the Posse Comitatus Act
Year Event
1878 (Congress enacts Posse Comitatus Act) "Congress enacted the Posse Comitatus Act of 1878 that placed strict limits on the military’s participation in civilian law enforcement duties.” (1)
1970 (National Guard called out against students) "... the Ohio National Guard was called out [by Governor James Rhodes] to put down an anti-war protest on the campus of Kent State University." (2)
1972 (Military called during seige) "During the siege [of Wounded Knee on the Pine Ridge Reservation in South Dakota], military was called in and used in several ways, including aerial reconnaissance flights, as undercover agents, and for advice in negotiations, logistics and rules of engagement." (2)
1981 (Posse Comitatus Act amended) "...Congress enacted a series of clarifying authorities and restrictions on the use of the military to assist law enforcement.14 Included in this law are several specific authorities in which the military can share information, training and equipment with law enforcement agencies.” (2)
1986 (first military anti-drug effort) “...Bolivia became the scene of the first major antidrug operation on foreign soil to publicly involve U.S. military forces. One hundred sixty U.S. troops took part in Operation Blast Furnace...” (2)
1988 (defense department to lead transit drug detection) “... the U.S. military’s active participation in America’s fight against illegal narcotics was further expanded by the George W. Bush administration through Public Law 100-456 that created amendments to USC Title 10, Chapter 18 [Military Support for Civilian Law Enforcement Agencies]. The changes to public law now required the Department of Defense (DoD) 'to serve as the lead agency for the detection and monitoring of aerial and maritime transit of illegal drugs into the United States.'” (1)
1989 (military task force formed to counter illegal drug flow) “In response to President George H.W. Bush’s declaration of the 'War on Drugs,' General Colin Powell, then Commanding General of the U.S. Army’s Forces Command, issued the order ... that established JTF-6 [Joint Task Force-Six] at Fort Bliss, Texas. JTF-6 was established to serve as the planning and coordinating operational headquarters to support local, state, and federal law enforcement agencies within the Southwest border region to counter the flow of illegal drugs into the United States.” (3)
1989 (military advisors deployed to South America) “President George H. W. Bush’s so-called 'Andean Initiative... involved the deployment of seven Special Forces teams and approximately 100 military advisors to Colombia, Bolivia and Peru to train the armies of the region to fight the drug war.” (4)
1989-1993 (military assistance increased to South America) “...the George H.W. Bush administration and U.S. congressional leaders committed to a five-year package of greatly increased counter-drug assistance to Colombia, Peru and Bolivia.” (2)
1990s (military monitoring of the 'air bridge') “United States Southern Command began a program called 'Support Justice' to assist in the aerial monitoring of the air bridge [used to transfer semi-refined cocaine from rural growing areas to processing plants and to destination countries] ... [and] to 'confirm anecdotal law enforcement information regarding the frequent use of small private aircraft to move ... cocaine'" (4)
1991 (Posse Comitatus Act amended to include counter-drug assistance) Via the National Defense Authorization Act for 1991, the Posse Comitatus Act was amended so that “during fiscal years 1991 through 2002, the Secretary of Defense may provide counter-drug activity assistance upon request of federal or state law enforcement agencies.” (5)
1993 (military counter-drug operations shift to South America) “President Clinton signed Presidential Decision Directive 14 (PDD 14),9 which shifted the focus of U.S. counter-drug operations from the 'transit zone in the Caribbean Sea and the Gulf of Mexico to the source zone, chiefly Colombia, Peru and Bolivia.'” (4)
1995 (military anti-drug task force expanded) “By directive of the Commanding General of U.S. Army Forces Command, JTF-6's area of responsibility was expanded to include the entire continental United States, Puerto Rico and the Virgin Islands.” (3)
1997 (innocent teenager killed by Marines) “... a teenager named Esequiel Hernández, a U.S. citizen, did not know that four U.S. Marines were concealed in camouflage in the area where he was herding goats while carrying a 22-caliber rifle, which he often did to protect the herd against snakes and other animals. At one point, one Marine felt that another concealed Marine was in danger because of the teenager and he opened fire, killing Hernández instantly.” (2)
1998 (military funds Colombian counternarcotics batallion) “... meeting in Cartagena, U.S. Defense Secretary William Cohen and Colombian Defense Minister Rodrigo Lloreda agreed to establish a Counternarcotics Battalion in the Colombian Army. The battalion, financed at first entirely by accounts in the U.S. defense budget.” (2)
2000 (military assistance for Colombian anti-drug missions) The U.S. Congress approved “a $1.3 billion package of mostly military aid to Colombia and its neighbors – a contribution to a larger strategy called “Plan Colombia” – the military’s resistance to anti-drug missions, whether counter-guerrilla or otherwise, wore away.” (2)
2001 (aircraft shot down killing missionary and daughter) Under the Air Bridge Denial (ABD) program, “... a Peruvian A-37 interceptor, operating as part of a joint U.S.-Peruvian counternarcotics mission, fired two salvos of machine gun fire into a small Cessna float plane after it had been identified as a probable drug trafficking aircraft. ... Two people on the aircraft were killed, a U.S. missionary and her infant daughter, both killed by the gunfire from the Peruvian aircraft. ... In the wake of the tragedy that took two innocent lives, programs in both Peru and Colombia were suspended pending a review of safety procedures.” (4)
2003 (air bridge monitoring resumes) ABD program restarts in Colombia. (6)
2004 (military anti-drug task force mission expanded) “JTF-6 was officially renamed JTF North and its mission was expanded to include providing homeland security support to the nation’s federal law enforcement agencies.” It’s mission statement is: “Joint Task Force North supports Drug Law Enforcement Agencies in the conduct of Counter Drug/Counter Narco-Terrorism operations in the USNORTHCOM area of responsibility to disrupt trans-national criminal organizations and deter their freedom of action in order to protect the homeland.” (3)(7)
2004 (air bridge monitoring changes trafficking patterns) Office of Congressman Mark Souder (R-IN) reported that Colombia ABD program “forced down and/or destroyed over 28 suspected narcotics trafficking aircraft, … seized 7.9 metric tons of illicit drugs ... [and] Resulted in changed narcotics trafficking patterns. (6)”
2006 (National Guard troops ordered to U.S./Mexico border) “President [George W.] Bush ordered 6,000 National Guard troops to assist the Border Patrol for a two-year period in California, Arizona, New Mexico, and Texas. ... They operated surveillance systems, analyzed intelligence, installed fences and vehicle barriers, built roads, and provided training.35 The deployment became known as 'Operation Jump Start.' This was the largest number of soldiers on the border since the Mexican Revolution ninety years earlier.” (2)
2006 (Posse Comitatus Act repealed) “President George W. Bush signed into law the Defense Authorization Act for Fiscal Year 2007. That Act included a section that essentially repealed Posse Comitatus: 'The Use of the Armed Forces in Major Public Emergencies.'29 It amended the U.S. Code to allow the president to use the military 'to restore public order and enforce the laws of the United States when, as a result of a natural disaster, epidemic, or other serious public health emergency, terrorist attack or incident, or other condition in any State or possession of the United States.'” (2)
2007 (Posse Comitatus Act restored) "When the [above] little-known provision in the FY 2007 Defense Authorization bill became more widely understood, the section was quickly repealed in the next year’s Authorization bill, thus restoring the effect of the Posse Comitatus Act." (2)
2007 (military anti-drug assistance to Mexico) At a “... meeting in Mérida, Yucatán, Presidents Calderón and Bush signed an agreement for a new security cooperation program, called the Mérida Initiative. This proposal provided Mexico and Central America with $1.6 billion in assistance, most of it military and police equipment and training, from 2008 to 2010.” (2)
2010 (National Guard troops ordered to U.S./Mexico border) “President Barack Obama announced the intention to send 1,200 National Guard troops to the border again. These troops will join the 340 already there under the 'State Counter Drug Programs,' assisting law enforcement with surveillance and intelligence gathering." (2)

(1) Luoma, Jr., Benjamin C., "The U.S. Military and Security along the U.S. Mexico Border: Evaluation of its Role in the Post September 11th Era," Naval Postgraduate School (Monterey, California: December 2002).…
(2) Withers, George; Santos, Lucila; and Isacson, Adam, "Preach What You Practice: The Separation of Military and Police Roles in the Americas," Washington Office on Latin America (Washington, DC: November 2010).…
(3) "History of Joint Task Force North," United States Department of Defense.…
(4) Huskisson, Major Darren C., "The Air Bridge Denial Program and the Shootdown of Civil Aircraft under International Law," Air Force Law Review (Maxwell AFB, Alabama: 2005) Vol. 56.…
(5) Doyle, Charles, "The Posse Comitatus Act and Related Matters: The Use of the Military to Execute Civilian Law," Congressional Research Service (Washington, DC: Library of Congress, June 1, 2000).…
(6) U.S. Representative Mark E. Souder, "Foreign Ops: Talking Points on Counternarcotics Efforts," (Washington, DC: Subcommittee on Criminal Justice, Drug Policy and Human Resources, 2005).…
(7) "Joint Task Force North Mission," United States Department of Defense.…