A classified 1965 USAF report suggested that the Red River flood control system could probably not be destroyed by conventional aerial bombing.
Heavy monsoon rains coupled with the preoccupation of the civilian population that normally maintained the water works, led to extensive flooding in 1971.
Given the North Vietnamese tactic of forcing U.S. aircraft to jettison their bombloads and abort their missions, the dikes undoubtedly were their point of impact on occasion, as they may have been for some downed U.S.
[4] As the North Vietnamese called on the local population to maintain the military lines of communication, labor was drawn away from dike maintenance.
The problem was exacerbated by the placement of air defense equipment (AA and GCI) on the dikes and the resulting deterioration caused by the vibration of the guns.
North Vietnamese SAMs that missed their mark often fell back to earth before exploding, causing additional damage to the dikes.
[7] Further complicating matters was the North Vietnamese placement of anti-aircraft radars, surface to air missiles, and artillery atop dike structures.
Although authorization was given during Operation Linebacker II to attack these sites, only the use of napalm, cluster bombs, and other antipersonnel weapons were permitted to be used in an attempt to minimize structural damage.