Citing "progress" in the Paris peace negotiations between National Security Advisor Henry Kissinger and Le Duc Tho of North Vietnam, President Richard Nixon halts the most concentrated bombing of the war, as well as mining, shelling, and all other offensive action against North Vietnam. The cessation of direct attacks against North Vietnam did not extend to South Vietnam, where the fighting continued as both sides jockeyed for control of territory before the anticipated cease-fire.
On December 13, North Vietnamese negotiators had walked out of secret talks with Kissinger. President Nixon issued an ultimatum to Hanoi to send its representatives back to the conference table within 72 hours "or else." The North Vietnamese rejected Nixon's demand and the president ordered Operation Linebacker II, a full-scale air campaign against the Hanoi area. This operation was the most concentrated air offensive of the war.
During the 11 days of the attack, 700 B-52 sorties and more than 1,000 fighter-bomber sorties dropped roughly 20,000 tons of bombs, mostly over the densely populated area between Hanoi and Haiphong. On December 28, after 11 days of intensive bombing, the North Vietnamese agreed to return to the talks. When the negotiators met again in early January, they quickly worked out a settlement. The Paris Peace Accords were signed on January 23 and a cease-fire went into effect five days later.