Western countries don't wage war in the way that lets you hold Afghanistan. Contrast with a successful historic conquering: "In the Mongol invasion of Khwarezm

Western countries don't wage war in the way that lets you hold Afghanistan. Contrast with a successful historic conquering: "In the Mongol invasion of Khwarezmia (1219–1221), Genghis Khan invaded the region from the northeast in one of his many conquests to create the huge Mongol Empire. His armies slaughtered thousands in the cities of Kabul, Kandahar, Jalalabad etc. After Genghis Khan returned to Mongolia, there was a rebellion in the region of Helmand which was brutally put down by his son and successor, Ogedei Khan, who put all male residents of Ghazni and Helmand to the sword in 1222; the women were enslaved and sold. Thereafter most parts of Afghanistan other than the extreme south-eastern remained under Mongol rule as part of the Ilkhanate and Chagatai Khanate." (Wikipedia) Modern gentlemans agreement wars only really work between modern Westernized industrial societies. The idea that you could ever nation build in Afghanistan on a mere 20 year period was laughable even in 2001. It's possible results would have been different given a multi-generational timeline but when you aren't annexing the country it's hardly worth the effort.