include the hundreds of aircraft lost during the interdiction campaigns or the crews that manned them. Scholars today remain divided on the merits of the electronic barrier system and the efficacy of the bombing campaigns that it directed. The claims of destruction made by the U.S. Air Force, both during and after the war, were originally taken as given. The only exception to this rule was at the CIA, which discounted Air Force claims at the time by as much as 75 percent. This was understandable due to the fact that the Vietnamese were basically silent during the 1970s and 1980s. By the 1990s, new historical research (especially by Air Force historians Earl Tilford, Bernard Nalty, and Jacob Van Staaveren) and the publications of the Military Institute of Vietnam finally opened new perspectives on aerial interdiction during the Vietnam War. The Seventh Air Force claimed that 46,000 PAVN trucks had been destroyed or damaged by air strikes during its tenure (with nineteen thousand of these occurring during Command Hunt V 1970–1971). While the North Vietnamese only imported 6,000 trucks into North Vietnam between 1968 and 1970 (for all of their operations), imports increased dramatically in 1971, though these also seem to have been as a result of the planned 1972 offensive. American claims that 80 percent of the materiel that started down the trail was destroyed while en route to the southern battlefields had to be altered in the face of loss claims of only 15 percent by the Vietnamese. Thomas C. Thayer, chief of the Advanced Research Projects Agency for four years during the war, believed that only about one-twentieth of the cargo imported into the north moved southward on the Ho Chi Minh Trail and that more than two-thirds eventually reached the battlefields in the south. More recently however, a new study by Air Force historian Eduard Mark established a correlation between trucks imported into North Vietnam during the war and those that were claimed by the American pilots as destroyed. Access to communist Vietnamese archives to scholarly research may add to the true effectiveness (or lack thereof) of the American electronic and aerial effort. Notes References Unpublished government documents United States, Military Assistance Command, Vietnam. Command History, 1968, Annex F. Military Assistance Command, Vietnam: Saigon, South Vietnam, 1969. United States, Military Assistance Command, Vietnam. Command History, Volume II, 1968, . Military Assistance Command, Vietnam: Saigon, South Vietnam,