1968
	29 January	It was announced that the successful North American X-15 programme was to be terminated by the end of the year.
	February	Arc Light B-52 Stratofortress bombing missions finally reached the authorised level of 800 sorties per month.
	29-30 January	North Vietnam launched the Tet Offensive, a large-scale attack by Viet Cong and NVA units throughout South Vietnam.
	March	Air support kept almost 7,000 isolated US Marines and South Vietnamese army troops at Khe Sanh from being annihilated by an estimated force of 40,000 North Vietnamese and Viet Cong surrounding the plateau.
	25 March	Operation Combat Lancer commenced when six F-111As of the 428th Tactical Fighter Squadron that had been deployed to Takhli, Thailand on 17 March, flew their first combat missions over Vietnam. Two were lost during the month and a third in April. Eventually 55 sorties were completed before the F-111s returned to the US.
	10 April	The Kadena-based detachment of the 9th Startegic Reconnaissance Wing began operations over Vietnam with the SR-71A.
	18 June	B-52 Stratofortresses completed more than 25,000 sorties, dropping over 63,000 tons of conventional bombs.
	26 september	The first production General Dynamics FB-111A startegic bomber had its maiden flight. It was intended as an interim replacement for the retired Convair B-58A and the cancelled North American B-70A.
	1 November	The last attack of Rolling Thunder was made against a target near Dong Hoi by an F-4D Phantom of the 8th Tactical Fighter Wing.
	1 November	President Johnson called to a halt Rolling Thunder operations against North Vietnam, as a part of a planned drawback of US military units to transfer the defence of South Vietnam to its own people. Attacks were to continue only in the demilitarised zone between North and South Vietnam.