The "Pentagon Papers" laid out the missteps taken by four administrations in their Vietnam policies. For example, they revealed the Johnson administration's obfuscations to Congress concerning the Gulf of Tonkin incidents that had led to direct U.S. intervention; they exposed the clandestine bombing of Laos that had begun in 1964; and they detailed the American government's complicity in the death of Ngô Đình Diệm. The study presented a continuously pessimistic view of the likelihood of victory and generated fierce criticism of U.S. policies.