Indeed, Afghanistan represents the triumph of the deterministic forces of geography, history, culture, and ethnic and sectarian awareness, with Pashtuns, Tajiks, Uzbeks and Hazaras and other groups competing for patches of ground. Tribes, warlords and mafia-style networks that control the drug trade rule huge segments of the country. To show just how perverted the situation has become, the British regional specialist Anatol Lieven, writing in The National Interest, argues that “just because the U.S. money was stolen does not mean that it was wasted,” since it has gone to paying off tribal chiefs to keep them from joining the Taliban or becoming feuding warlords.

It did not have to be like this. Had the United States not become diverted from rebuilding the country by its invasion of Iraq in 2003 (which I mistakenly supported), or had different military and development policies been tried, these forces of division might have been overcome. According to the Pakistani journalist Ahmed Rashid, there was simply too much emphasis on the electoral process in Kabul and not nearly enough on bread-and-butter nation building — in particular, bringing basic infrastructure and agriculture up to the standards that Afghans enjoyed from the 1950s until the Soviet invasion of 1979.

Certainly, no place is hopeless. But that is not where we are now. The heavily Pashtun Taliban, an accessory to the Sept. 11 hijackings, continues to make battlefield gains and, if there are actual peace negotiations, is poised to share power with the American-backed government of President Ashraf Ghani, if not eventually replace it. The United States’ special adviser to Afghanistan, Zalmay Khalilzad, is trying to broker a diplomatic solution that allows the United States to draw down its forces without the political foundation in Kabul disintegrating immediately.

That may be the real reason the United States keeps spending so heavily in Afghanistan. The Pentagon is terrified of a repeat of 1975, when panicked South Vietnamese fled Saigon as Americans pulled out and North Vietnamese forces advanced on the city. The United States military did not truly begin to recover from that humiliation until its victory in the Persian Gulf war of 1991. An abrupt withdrawal from Afghanistan could conceivably provide a new symbol of the decline in American hard power.

There is also the fear that an Afghanistan in chaos could once again provide a haven for an international terrorist group determined to perpetrate another Sept. 11-scale attack. Of course, Yemen, Somalia and a number of other places could also provide the setting for that.