Đồng Tâm Base Camp was established on the northern bank of the Mekong River 7 km west of Mỹ Tho upon COMUSMACV General William Westmoreland's decision to gain full control over the upper Mekong Delta region.

[2] The Vietcong attempted to sabotage the base construction sinking the dredgeship Jamaica Bay on 9 January 1967 with the loss of 3 crewmembers.

In April the US Navy River Assault Squadron 9 was deployed to Đồng Tâm to support operations.

[2]: 189 On 1 June 1967, the Mobile Riverine Force (MRF) comprising the 2nd Brigade, 9th Infantry Division and the US Navy River Assault Squadrons 9 and 11 was established at Đồng Tâm.

By this time the base occupied 12 square kilometres and included a 500m runway and a loading basin for boats.