On 10 May 1966 following sightings of large People's Army of Vietnam (PAVN) forces west of Đức Cơ and Plei Me Camps, the 3rd Brigade, 25th Infantry Division was deployed to Landing Zone Oasis to sweep the area to the southwest.

[1] On the morning of 24 May a CIDG patrol was ambushed by an estimated two battalions of PAVN 10 kilometres southwest of Plei Djereng Camp.

On the morning of 25 May, the PAVN attacked the CIDG positions and they withdrew in a running firefight towards Plei Djereng, losses were 18 Montagnards and 2 US Special Forces advisers.

[1]: 289–90 The 3rd Brigade then searched south and west of LZ Ten Alfa for the next 8 days but were unable to locate the PAVN who had presumably withdrawn across the border into Cambodia.

On 20 June the 2/35th Infantry's reconnaissance platoon, operating 10 kilometres north of the Chu Pong Massif pursued a group of PAVN soldiers and was pinned down by heavy fire and had to be rescued by the Battalion and Troop C 3rd Squadron, 4th Cavalry Regiment, US losses were 3 killed and 14 wounded.

[2] This article incorporates public domain material from websites or documents of the United States Army Center of Military History.