In terms of both legitimacy and plain common sense, the US attack on Afghanistan in 2001 should have had a very limited objective -- to decapitate al Qaeda by eliminating its leadership and command/control assets in that country. Adding a "nation-building" objective queered the plan from the very start (I've been saying this for oh, about eight years, btw).

The six weeks that the US forces spend mucking around in the lowlands -- defeating the Taliban and installing a puppet regime as a precursor to the "nation-building" exercise -- before addressing Tora Bora gave Osama bin Laden and Co. ample time to pack their trash and depart for Pakistan in an orderly manner, leaving the al Qaeda threat largely intact. While it would be a stretch to blame every subsequent al Qaeda attack (London, Madrid, Turkey, Indonesia) on the US failure to focus on mission, that failure no doubt contributed to al Qaeda's ability to plan and carry out those attacks.

To put a finer point on it, the US failed in its legitimate/common sense objective in Afghanistan right off the bat. This was not due to any deficiency in its armed forces, which achieved their assigned tactical objectives in good order, but rather to a refusal on the part of the National Command Authority, i.e. the president and his advisors, to live in the real world.

The US has now occupied Afghanistan for 8 years, and fully 7 1/2 of those years have been spent dribbling American blood into the ground and throwing American treasure at a failed pursuit of neoconservative fantasy objectives (and a very, very successful pursuit of "transfer money from American taxpayer pockets to 'defense' contractor bank accounts" objectives).

The problem with Afghanistan, from a US military perspective, is that it is not Japan or Germany circa the mid-20th century. It is not a state by any reasonable definition of the word.

Germany and Japan both became modern nation-states by the late 19th century, and by the 20th century the people living in those countries had been broken to the habit of looking to a central capital (Berlin or Tokyo) and to a central government (Reichstag, Diet), to a chief executive (emperor, fuhrer, whatever) as the source of political authority. Capture the capital, take over the government, receive the surrender of the leader, and the people would bow to whatever new regime was imposed.

Afghanistan is not like that. It's not a state. It's a stretch to call it a country. It's central Asia's political insane asylum, a crazy quilt of tribal and religious alliances and a patchwork of tiny warlord fiefdoms that no neighbor in its right mind would attempt to annex and that no single domestic government can reasonably aspire to rule. At the height of its power, the Taliban had working arrangements with enough of the warlords to pass itself off as a "national government" ... as long as it only acted like one in form and never attempted to do so in substance.

Prior to the US invasion, the Taliban controlled the government district in Kabul and a few scattered military bases, and the warlords ran the rest. Eight years after the US invasion, the US and the Karzai government control the government district in Kabul and a few scattered military bases, and the warlords run the rest. The only substantial difference is that while the Taliban faced only minor competition for the allegiance of the warlords (the Northern Alliance), the Taliban are serious competitors for those allegiances versus the Karzai regime and the occupation forces.

This is not a problem for which a military solution exists. There's no flag to capture. There's no capital to take. There's no conventional army to defeat. There's no leader who can break his sword over his knee, hand it to General Stanley McChrystal, and bring hostilities to an end. And the addition of four thousand, forty thousand, or four hundred thousand US troops to the mix won't change that. Pissing harder upwind is still pissing upwind. Time to stick it back in our pants and zip up, guys.

Afghanistan today looks pretty much like it did before the US forces arrived -- and that's pretty much the same way it's going to look after the US forces leave. The only relevant question, then, is how many more American lives are going to be lost, and how many more American dollars spent, before we face that reality?