 The main assault began on the night of May 16, after an intense aviation and artillery bombardment.While motorized rifle battalions, preceded by reconnaissance units, attacked the dominating features at the entrance of the valley, airborne units were airlifted by helicopter behind the main Mujahideen defenses.In all, 4,200 troops were airlifted into the valley to capture strategic points, right up to the Pakistani border, in an effort to cut the Mujahideen supply lines.