High quality reprint of this recently declassified 1968 study.Operation NIAGARA was a concentrated air effort executed by the 7th Air Force Commander in early 1968 to disrupt a potential major offensive in northwestern I Corps and the contiguous area of Laos An extensive enemy build-up in the western DMZ area in late 1967 and early 1968 indicated that a major offensive was developing, with the estimated objective of overrunning Khe Sanh and other friendly positions located astride Route 9--the most readily accessible infiltration route for North Vietnamese forces bypassing the DMZ into South Vietnam It was further estimated that the enemy would launch his offensive on or about 30 January-when the South Vietnamese would be observing the Lunar New Year Thus, at the direction of COMUSMACV, the 7th Air Force Commander and his operations and intelligence staff planned and directed SLAM-type operations in the NIAGARA area several days prior to the Tet Holidays. These operations were accorded the highest priority, and were applied on a sustained basis SLAM-type operations began in the NIAGARA area on 22 January, with 595 tactical strike sorties (including 7AF, USMC, and USN) and 49 B-52 sorties flown against enemy targets When Operation NIAGARA officially terminated on 31 March 1968, over 24,400 tactical strike sorties and 2,500 B-52 sorties had been flown This was the greatest sustained concentration of airpower in the Vietnam conflict to date The purpose of this report is to bring the statistical weight of effort into proper perspective through the narrative study and documentation of significant developments It addresses in particular those operational areas of 7th Air Force evaluative concern-i.e. operational problems and lessons learned, coordination and control, the development of targets and tactics, and the responsiveness of airpower to the tactical situation.