The Vietnam war, was, IMHO both a strategic and a tactical defeat for the USA and it's allies.
The first strategic blunder was not identifying Ho Chi Minh as a nationalist, because cold-war blinkers had typecast him as
just a communist. The Second strategic blunder was the conflict between the need to woo DeGaulle for his participation in NATO prompted the US to get involved in [formally] French Indo-China.
At the operational level, the leadership was lacking. Generals like Westmoreland were gurus at conventional warfare, and had proved their expertise in WW2. They were not so good at COIN. Yet the US did have some good COIN officers, such as John Paul Vann, but failed to take note of their advice, and failed to promote them.
http://en.wikipedia.org/wiki/A_Bright_Shining_LieThe US also pissed about a lot. It should not have supported the RSVN governments, which were corrupt, and did not enjoy the confidence and support of the people. But the US self-deluded itself into thinking it could either reform the South Vietnamese govt, or it just pretended that the corruption was not there.
Tactically, operations involving officers like the US Col. Paul Vann, and allied operations involving the Australian Task force were a better model for winning the war.
Even elite US troops have lost their balance. The balance I am talking about is when to use "rock and roll" and when to use human assets. To try to preserve their soldiers lives by using air or artillery is a laudable concept, but it can be overdone.
Under the British and Australian system, the army uses patrolling to gain information and security. For example, at dawn and dusk, Pommies or Aussies use clearing patrols to secure against attack. The US army tends to use arty, air, or firepower to clear the area surrounding a base preemptively. [That is, to fire into no-mans-land to try to deter an enemy who only might be there]. I even saw a documentary where a US Green Berets used firepower instead of a clearing patrol.
The USA and military did not get the media on board like they did in WW2. Thus, the war was lost before a shot was fired because the public [quite rightly] became too sensitive to casualties in a war it did not understand or agree with. There was just too much hypocrisy and duplicity involved for the American public to maintain it's political will to fight. People soon saw through the nationalistic hype and "Yellow peril", anti-communist propaganda. Not that most Americans loved communism, but they could see from the McCathy era how crazy and obsessed the rabid anti-communists were.
DBD is a fun username. I do not imagine myself as a reincarnation of T.H. Huxley, and with respect, neither should you.