On 7 January 1971 MACV was authorized to begin detailed planning for an attack against PAVN Base Areas 604 and 611. The task was given to the commander of XXIV Corps, Lieutenant General James W. Sutherland, who had only nine days to submit it to MACV for approval. The operation would consist of four phases. During the first phase U.S. forces inside South Vietnam would seize the border approaches and conduct diversionary operations. Next would come an ARVN armored/infantry attack along Route 9 toward the Laotian town of Tchepone, the perceived nexus of Base Area 604. The village was estimated to have had about 1,500 inhabitants in 1960; five years later, half of the residents had fled due to war; Operation Lam Son 719 then destroyed the village and left it deserted. This advance would be protected by a series of leap-frogging aerial infantry assaults to cover the northern and southern flanks of the main column. During the third phase, search and destroy operations within Base Area 604 would be carried out and finally, the South Vietnamese force would retire either back along Route 9 or through Base Area 611 and exit through the A Shau Valley. It was hoped that the force could remain in Laos until the rainy season was underway at the beginning of May. U.S. planners had previously estimated that such an operation would require the commitment of four U.S. divisions (60,000 men), while Saigon would only commit a force less than half that size.