During the summer and fall of 1967, the center of activity shifted to the eastern DMZ area. After being battered and thrown for a loss on their end sweep, the Communists concentrated on the middle of the line again. With an estimated 37 battalions poised along the border, the NVA constituted a genuine threat to the northernmost province. At times as many as eight Marine battalions were shuttled into the area for short-term operations and three or four were there full time, but the enemy's intensified campaign created a demand for more troops. As a result, General Westmoreland was forced to make major force realignments throughout South Vietnam to satisfy the troop requirements in I Corps.(14)
General Westmoreland drew the bulk of these reinforcements from areas in Vietnam which, at the time, were under less pressure than the five northern provinces. During April and May 1967, Task Force OREGON, comprised of nine U. S. Army battalions from II and III Corps, moved into the Chu Lai-Duc Pho region and was placed under the operational control of General Walt. By the end of May, five battalions of the 5th and 7th Marines at Chu Lai had been released for service further north. Two of these units moved into the Nui Loc Son Basin northwest of Tam Ky to conduct offensive operations and support the sagging Vietnamese Revolutionary Development efforts. The other three settled in the Da Nang tactical area of responsibility (TAOR) and in turn released two Marine battalions, 1/1 and 2/1, which moved to Thua Thien and Quang Tri provinces.
In addition to his in-country assets, General Westmoreland also called on Admiral U. S. Grant Sharp, Commander in Chief, Pacific, for reinforcements. Besides the two Special Landing Forces afloat with the U. S. Seventh Fleet, the Pacific Command maintained a Marine Battalion Landing Team (BLT 3/4) as an amphibious reserve on Okinawa.[7](15) Actually, this unit was part of the BLT rotation system whereby battalions were periodically shuttled out of Vietnam for retraining and refurbishing in Okinawa before assignment to the SLF. ComUSMACV needed the unit and got it. On 15 May, 3/4 began an airlift from Okinawa to Dong Ha by Air Force and Marine C-130 aircraft and within 31 hours the 1,233-man force was in-country. After the realignment of units in I Corps was complete, there was a net increase of four USMC battalions in the DMZ area making a total of seven. Additionally, the SLFs, cruising off the Vietnamese coast, provided two more battalions which could be landed quickly and added to the III MAF inventory. SLF Alpha (BLT 1/3 and HMM-362) was placed on 24-hour alert to come ashore and SLF Bravo (BLT 2/3 and HMM-164) was given a 96-hour reaction time.(16)