What is the reason for the Afghan War? Women's Rights? Nation building ? "War on Terror" ? All have been put forth at one stage or another as the reason for "staying the course" there after a decade of conflict since the US invaded in 2001.All official pretexts are half truths and rationalisations. More "Public Diplomacy".
It has always been the strategic goal to bring about the construction of the TAPI Pipeline first and foremost:without it none of the secondary goals, even if the US was not espousing them for propaganda reasons, would be difficult without integrating Afghanistan into the regional economies through the pipeline project.
The value of it to the US and NATO is that "energy independence" means, effectively, not relying on Iran's IPI rival pipeline. By blocking off Iranian interests to the East whilst now also attempting to destabilise and overthrow the pro-Iranian Assad regime in Syria, the geopolitical game plan is clear.
This truth is never made available to the British public who are spun a set of half truths and kitsch about "our boys", as if their sacrifice is about protecting us at home. Hence the use of "the war on terror" intermittently to rationalise the sacrifice. The electorate is too fickle to understand the real
In fact, the US was colluding with the Taliban before the events of 9/11 made that strategy impossible to back. It had been parts of Pakistan's political elites which created the Taliban in the 1990s in the first place so as to control Helmland and secure the pipeline route.
It should be remembered that Helmland, this low lying region in which most British troops have been killed by Taliban roadside IEDs, is the only possible transit route for Turkmenistan's gas south towards the Indian subcontinent. British troops have been used to secure a pipeline route on a "The Grand Chessboard"
Now, if that is considered "worth it", do remember that the US is at the same time trying to negotiate with the Taliban and Vice President Joe Biden does not regard the Taliban as "terrorists". The goal is constant: the pipeline. US companies are bidding at present to win the contract to build it.