Although the NVA encircled the KSCB and applied constant pressure, the defenders were never restricted entirely to the confines of the perimeter. The term "siege," in the strictest sense of the word, was somewhat of a misnomer because the Allies conducted a number of daily patrols, often as far as 500 meters from their own lines.[26](90) These excursions were primarily for security and reconnaissance purposes since General Tompkins did not want his men engaged in a slugging match with the enemy outside the defensive wire. If the North Vietnamese were encountered, the Marines broke contact and withdrew, while supporting arms were employed.(91) One vital area was the drop zone. When the weather turned bad in February, the KSCB was supplied primarily by parachute drops. Colonel Lownds set up his original zone inside the FOB-3 compound but later moved it several hundred meters west of Red Sector because he was afraid that the falling pallets might injure someone. Lieutenant Colonel Mitchell's 1/9 was given responsibility for security of the drop zone and his patrols conducted daily sweeps along the periphery of the drop area to flush out enemy troops who might try to disrupt the collection of supplies. In addition, combat engineers swept through the zone each morning and cleared out any mines the enemy set in during the night. Thus the defenders at Khe Sanh were never completely hemmed-in, but the regimental commander admitted that any expedition beyond sight of the base was an invitation to trouble.(92) The Allies did more than prepare defenses and conduct patrols because the NVA launched three of its heaviest ground attacks during the first week in February. In the predawn hours of 5 February, the North Vietnamese lashed out at the Marine base and adjacent outposts with nearly 200 artillery rounds while a battalion from the =325C NVA Division= assaulted Hill 861A. Colonel Lownds immediately placed all units on Red Alert and, within minutes, 1/13 was returning fire in support of E/2/26.