 Moreover, the 272d Regiment, the 1st and 7th Battalions of Military Region IV under the VC 165th Regiment, the Phu Loi Local Force Battalion, plus three local force companies, as well as the 2d, 3d, and 8th Battalions of the 165th Regiment were suspected to operate in the Iron Triangle.To strike against this enemy force, II Field Force organized the single largest ground operation of the American War in Vietnam involving the equivalent of three US divisions, some 30,000 US and South Vietnamese troops.The US units involved were the 1st and 25th Infantry Division, the 196th Infantry Brigade, the 173rd Airborne Brigade, as well as the 11th Armored Cavalry Regiment.