By 1969, North Vietnamese and Viet Cong forces had established well-protected sanctuaries just across the Cambodian border, from which they launched raids into South Vietnam. Previous U.S. policy had largely avoided striking these areas to prevent widening the war. President Richard Nixon, however, chose to change course. On March 18, 1969, he secretly authorized a series of B-52 raids on Cambodian territory, marking the beginning of Operation Menu. The first target was Base Area 353, believed by American intelligence to contain the Communist headquarters for all of southern Vietnam.

The bombings were carried out under a veil of secrecy unprecedented in the war. Official records of the missions reported false locations inside South Vietnam, and only a handful of senior military and civilian officials were aware of the true targets. Even within the U.S. government, knowledge of the operations was tightly restricted, ensuring that for a time almost no one outside the inner circle knew that Cambodia was being bombed.

Operation Menu continued for a full year, with a series of raids codenamed Breakfast, Lunch, Dinner, Dessert, Snack, and Supper. Eventually, the campaign expanded into open bombing of Cambodian sanctuaries in 1970, sparking intense controversy in the United States and further destabilizing Cambodia. What had begun in secret on March 18, 1969, soon became one of the most contentious aspects of Nixon’s Vietnam policy, exposing the deepening complexity of a war that was already spilling across borders.