There were increasing signs of heavy logistical activity in southeastern Laos, activity which heralded just such a North Vietnamese offensive. PAVN offensives usually took place near the conclusion of the Laotian dry season (from October through March) and, for PAVN logistical forces, the push to move supplies through the system came during the height of the season. One U.S. intelligence report estimated that 90 percent of materiel coming down the Ho Chi Minh Trail was being funneled into the three northernmost provinces of South Vietnam, indicating forward stockpiling in preparation for offensive action. This build-up was alarming to both Washington and the American command, and prompted the perceived necessity for a spoiling attack to derail future North Vietnamese objectives.