Operation Desert Rat (16 February – 3 April 1971) was a diversionary attack by a Laotian irregular regiment upon the crucial communist supply line, the Ho Chi Minh trail. Carried out by the Central Intelligence Agency sponsored Groupement Mobile 33, the Desert Rat offensive struck the rear of the 50,000 North Vietnamese troops combating Operation Lam Son 719 beginning on 16 February 1971. With 16 daily tactical air sorties and airborne forward air controllers available, the Desert Rat guerrillas used their hilltop position near Moung Phine to spot targets for bombing. It also raided, skirmishing 110 times, killing 121 communist soldiers, and sowing 1,500 mines along North Vietnamese lines of communication. On 20 March, it was assaulted by two communist battalions. The major threat of Lam S