The Vietcong also had the advantage in that they could easily hide in South Vietnamese villages from US soldiers, but the American Troops were so distinctive, they could be spotted anywhere by the Vietcong.
It could be argued that because for the speed in which the US was deploying troops, many of those called up were not fully trained, and therefore unable to fight to the best of their ability.
The lack of support for the US soldiers and the war in general was another major factor in the US defeat. The South Vietnamese were initially neutral towards the war, but as US tactics became more aggressive, they began to assist the Vietcong. This made it very difficult to effectively combat the Vietcong, because, as mentioned earlier, the Vietcong could hide amongst the villagers of South Vietnam. As a result, the US troops began to use violent Search and Destroy tactics, going in to a village and sorting through the Villagers. These grew in violence until the events of My Lai, in which US troops violently massacred hundreds of villagers. It was at this point they lost the support of the US population.
Losing the support of the American Public was a big problem for the US in Vietnam. The US government was under huge pressure to end the war. This had direct impact on the US Troops on the frontline, Budgets were cut, reinforcements were lessened and the Equipment they were relying on was no longer being properly maintained. It was also very demotivational for the US troops. They the lost the support of not only their Vietnamese Allies, but also their Families back in the US.
The culmination of these factors led to the withdrawal of US troops from Vietnam and a sense of defeat for the soldiers who were returning. It was not the tactics of the US troops that lost them the war, It was the lack of support, the superior Vietcong tactics and their inability to adapt to the situations as they became apparent.