Such losses underscored the need for a third battalion and the requirement for tanks to support the infantry; a realisation which challenged the conventional wisdom of Australian counter-revolutionary warfare doctrine which had previously allotted only a minor role to armour. Yet, it would be nearly a year before more Australian forces would finally arrive in Vietnam. To Brigadier Stuart Graham, the 1 ATF commander, Operation Bribie confirmed the need to establish a physical barrier to deny the Viet Cong freedom of movement and thereby regain the initiative, and the subsequent decision to establish an barrier minefield from Đất Đỏ to the coast increasingly came to dominate task force planning. Yet ultimately this would prove both controversial and costly for the Australians, and despite initial success, the minefield would become a source of munitions for the Viet Cong to use against 1 ATF and later the decision would be made to remove it in 1969. Meanwhile, as the war continued to escalate following further American troop increases, 1 ATF was heavily reinforced in late 1967. A third infantry battalion arrived in December 1967, and a squadron of Centurion tanks and more Iroquois helicopters were added in early 1968. In all a further 1,200 men were deployed, taking the total Australian troop strength to over 8,000 men, its highest level during the war. This increase effectively doubled the combat power available to the task force commander.