Our involvement in Afghanistan is untenable because the country is untenable.  No matter what is done, Afghanistan will fail because of its galloping population growth.

When the U.S. became involved in 2001, the country had a population of 20.5 million.  Now it is 34.4 million, up nearly 70 percent.  In the intervening 16 years, the U.S. spent about one trillion dollars and 2,000 lives in stabilizing Afghanistan.  All the stability and free food provided just created a perfect breeding environment for the natives.

The population growth rate has settled at 3.0 percent per annum.  At that rate, in another 16 years, there will be 55.2 million Afghans, most of whom will need imported grain to keep body and soul together.  The Afghani proclivity to breed will only be curbed by starvation.  That will happen at some stage because, even if we wanted to underwrite that population expansion, getting the necessary quantity of food into the country will become more and more difficult.  Perhaps that situation is beginning now.  The U.N.'s Food and Agriculture Organization has reported that 8.4 million Afghans are in an acute food insecurity crisis.

The Afghan government budget is $8 to $10 billion per annum, of which it raises about $2 billion.  The balance is mostly provided by the U.S. taxpayer.  That is also untenable in the long term.

To put all this into context, let's revisit the recent history of Afghanistan, back to 2008.  In the presidential campaign of that year, Barack Obama characterized Iraq as the "bad war" and Afghanistan as the "good war."  It was easy to predict that President Obama would not direct a withdrawal because of what he had said in the 2008 campaign.  And that meant that the can was kicked down the road for another eight years. 

The withdrawal from Afghanistan will be physically difficult, because everyone knows that the place will collapse as soon as the U.S. leaves, and security for the last servicemen out will be problematic.  In fact, it may have to be a fighting retreat.  There is another major complication looming in that our next major war is likely to be with China, which will initiate proceedings with the maximum disruption and stress on the U.S. command structure.  The airbase at Bagram is only 400 miles from the Chinese border.  It and other bases with U.S. troops are likely to be bombed at the outset of a war.  Not only are our outposts in Afghanistan a waste, but they will make us more vulnerable in a war we need to win.

Afghanistan will go back to being a hellhole run by the Taliban, who will go back to plotting attacks on us.  But that is easily dealt with by the Trump policy of banning types of unpleasant people from entering the country.  At least that is something that the president has tried to do so far.  It will become imperative. 

David Archibald is the author of American Gripen: The Solution to the F-35 Nightmare.