//NJ, if that was the point Douglas was making, then he like you ... and Jno ... raced ahead of the question which was ‘what should the west have done in response to 9/11’.//
It wasn't an answer to the question directly, no. It was more a suggestion of what should not have been done. The US and UK's action in invading Afghanistan was nothing short of a Crusade, only with aircraft instead of horses. In the last 200 years there have been at least five attempts to "tame" Afghanistan (i.e. to bring them round to our way of thinking). There were three attempts by the British, one by the Russians and now one by an allied force of the US and the UK plus others. All failed. It should by now have crossed the minds of the people inclined to embark on these quests that Afghans do not want to be brought round to our way of thinking. And nor they should.
It was reported today that the main reason the Taliban succeeded so easily in taking control, when they were outnumbered by a home security force as least twice as large and certainly better equipped, was simply down to one thing - money. Ever since the US/UK withdrawal was announced - and probably before - the Afghan troops and many of the police have not been paid. Instead, money earmarked for their pay, provisions and ammunition (mainly in the form of grants from the US) has been salted away by the president and senior ministers and officials into Swiss bank and Middle Eastern accounts, ready for use when they up sticks. It is little wonder the troops and police handed over power so readily. Why should the US and UK continue to spend money and risk lives when the country's leaders have so few scruples?
The US has spent enormous sums in the last 20 years in that wretched place. Some estimates place it at more than $250bn. The UK has probably spent a similarly unaffordable sum. President Biden's decision was the correct one and the simple answer to the question in this post was that whatever they did following 9/11, the West should have learned the lessons from the last 200 years, and not gone anywhere near Afghanistan.