President Johnson halted bombing above the 20th parallel of longitude in North Vietnam on 1 April 1968. On 1 November 1968, he would entirely end the bombing of North Vietnam, closing Operation Rolling Thunder.Summers, Karnow, p. 96. 

 These halts would cause a redirection of American air power toward the Ho Chi Minh Trail, and an increased need for forward air control there.  

 North Vietnamese AAA defenses burgeoned along the Trail.  COULD USE SOME STATS HERE!  

 US fooled itself into believing it was destroying trucks faster than communists could import them from USSR and China.  MIGHT COULD USE SOME STATS HERE ALSO.