Operation Linebacker was the codename of a U.S. Seventh Air Force and U.S. Navy Task Force 77 air interdiction campaign conducted against North Vietnam from 9 May to 23 October 1972, during the Vietnam War. Its purpose was to halt or slow the transportation of supplies and materials for the Nguyen Hue Offensive (known in the West as the Easter Offensive), an invasion of the South Vietnam by the North Vietnamese People's Army of Vietnam (PAVN) that had been launched on 30 March. Linebacker was the first continuous bombing effort conducted against North Vietnam since the end of Operation Rolling Thunder in November 1968. Nguyen Hue Offensive At midday on 30 March 1972, 30,000 PAVN troops, supported by regiments of tanks and artillery, rolled southward across the Demilitarized Zone (DMZ) that separated the two Vietnams. This three-division force caught the Army of the Republic of Vietnam (ARVN) and their American allies unprepared. The PAVN force struck the defensive positions of the ARVN 3rd Division and threw it into disarray. ARVN forces then fell back, and a race began between both belligerents to the bridges at Đông Hà and Cam Lộ. By 4 April, ARVN officers had patched together a defensive line that held the PAVN at bay, but it was only a temporary respite. Although the conventional attack by the PAVN, which included the extensive use of armor and heavy artillery, riveted the attention of the allies on the northern provinces, it was only the first of three such operations that were launched that spring. On 5 April, a PAVN force of 20,000 crossed the border from their sanctuaries in Cambodia in another three-division, combined arms force to attack Bình Long Province, north of Saigon. They quickly seized the town of Lộc Ninh and then surrounded the town of An Lộc, cutting the road to the capital. On 12 April, the PAVN struck again, this time moving in from eastern Laos and seizing a series of border outposts around Đắk Tô in Kon Tum Province in the Central Highlands. The PAVN then proceeded east toward the provincial capital of Kon Tum. Hanoi had initiated the offensive to coincide with the winter monsoon, when continuous rain and low cloud cover made air support difficult. The initial U.S. response to the offensive was lackadaisical and confused. The Pentagon was not unduly alarmed and the U.S. Ambassador and COMUSMACV, General Creighton W. Abrams,