[8] The system was an anti-infiltration barrier just south of the DMZ. Obstacles were used to channelize the enemy. Strongpoints, such as Con Thien, served as patrol bases and fire support bases.
[9] In addition to the action near the DMZ, there was one other area in I Corps that was a hub of activity. The Nui Loc Son Basin, a rice rich coastal plain between Hoi An and Tam Ky, was the operating area of the =2d NVA Division=. Between April and October 1967, Marine, U. S. Army, and ARVN troops conducted 13 major operations (including 3 SLF landings) in this region and killed 5,395 enemy soldiers. By the end of the year, the =2d NVA Division= was temporarily rendered useless as a fighting unit.
[10] The official designation of the unit at Khe Sanh was Regimental Landing Team 26 (Forward) which consisted of one battalion and a lightly staffed headquarters. The other two battalions were in-country but under the operational control of other units. The rest of the headquarters, RLT-26 (Rear), remained at Camp Schwab, Okinawa as a pipeline for replacements. RLT-26 (Forward) was under the operational control of the 3d MarDiv and the administrative control of the 9th MAB. Any further mention of the 26th Marines will refer only to RLT-26 (Forward).
With the beginning of the new year, Khe Sanh again became the focal point of enemy activity in I Corps. All evidence pointed to a North Vietnamese offensive similar to the one in 1967, only on a much larger scale. From various intelligence sources, the III MAF, 3d Marine Division, and 26th Marines Headquarters learned that NVA units, which usually came down the "Santa Fe Trail" and skirted the combat base outside of artillery range, were moving into the Khe Sanh area and staying.[11](33) At first, the reports showed the influx of individual regiments, then a division headquarters; finally a front headquarters was established indicating that at least two NVA divisions were in the vicinity. In fact, the =325C NVA Division= had moved back into the region north of Hill 881N while a newcomer to the area, the =304th NVA Division=, had crossed over from Laos and established positions southwest of the base. The =304th= was an elite home guard division from Hanoi which had been a participant at Dien Bien Phu.[12](34) The entire force included six infantry regiments, two artillery regiments, an unknown number of tanks, plus miscellaneous support and service units. Gradually, the enemy shifted his emphasis from reconnaissance and harassment to actual probes and began exerting more and more pressure on Allied outposts and patrols. One incident which reinforced the belief that something big was in the wind occurred on 2 January near a Marine listening post just outside the main perimeter.(35)