In this same report Laird noted that the war had commanded more of his attention than any other concern during his four-year term. Upon becoming secretary he set up a special advisory group of DoD officials, known as the Vietnam Task Force, and he met with them almost every morning he was in the Pentagon. He also visited Vietnam several times for on-the-scene evaluations. Although his program of Vietnamization could be termed a success, if one considers the progress of troop withdrawals, U.S. involvement in the conflict became perhaps even more disruptive at home during Nixon's presidency than during Johnson's. The U.S. incursion into Cambodia in May 1970 to eliminate North Vietnamese sanctuaries, the renewed bombing of North Vietnam and the mining of its harbors in May 1972 in response to the North Vietnamese Easter Offensive and another bombing campaign against the North in December 1972 brought widespread protest. Nixon's Vietnam policy, as well as that of previous administrations, suffered further criticism when, in June 1971, the Pentagon Papers, a highly classified narrative and documentary history of U.S. involvement in Vietnam from 1945 to 1967, prepared at Secretary McNamara's order, was leaked and published in part in several major newspapers.