Zenpundit discusses strategy, power and diffusion:
A recent estimate for the cost of the war in Afghanistan by the Congressional Research Office is $443 billion dollars to occupy and fight a Pakistani-supported insurgency in a primitive country whose annual GDP is a mere $27 billion. A figure that itself inflated by $3-4 billion in remittances, $4 billion in NGO aid and $14 billion in direct US aid (2010 figure); when you then subtract opium smuggling ($4 billion), Afghanistan’s legitimate economic activity may only be a miniscule GDP of $2–3 billion.
This does not, of course, include the cost of ten years of lavish bribes for Pakistan, a portion of which was used by the ISI to support the Taliban killing American and ISAF soldiers and Afghan civilians.
This is not a cost-effective or strategic way to run a war. In fact, even for a nation as wealthy as the United States there is nothing in Afghanistan worth such an expenditure of blood and treasure, especially when the bulk of our enemies appear to be based in Pakistan, not Afghanistan.
William Lind and the 4GW school used to like to make the point, regarding your moral and political legitimacy, that “If you fight the weak, you become weak”. The corollary to that is economic: “If you fight the poor, you become poor”.
Grinding poverty itself is a tax upon the invading force. There are no resources for your army to commandeer or buy, no skilled manpower to requisition or hire, no infrastructure for them to use. All of that must be imported and built at great expense by the invader whose troops are accustomed to far less spartan environs. The local population is usually malnourished, illiterate, ignorant, suspicious of outsiders and rife with disease; their living habits and water sources unsanitary and endanger the troops. Caring for the locals, even minimal administration of humanitarian aid, becomes a bureaucratic and logistical burden consuming time and diverting resources away from urgent military needs.
The United States under George Bush the Elder, entered into Somalia, a land beset by violent anarchy and it’s people in the grip of a terrible famine and was driven out shortly thereafter under Bill Clinton. The last scenes there being the emaciated Somali followers of a two-bit warlord, Mohammed Farah Aidid, gleefully swarming over and looting our military’s former… garbage dump.
When the enemy has a land so poor that he treasures and makes use of the crap you throw away, the economic spillover of your logistical supply lines will fund his war against you. Used to surviving on bare subsistence, the invader’s presence becomes an economic bonanza for resistance and collaborator alike. Sort of a highly kinetic form of military Keynesianism. The war itself and the occupation become an irreplaceable cornerstone of their economy. They hate you being there, but can’t afford to defeat you and drive you out either — making a “quagmire” irregular conflict their ideal economic equilibrium to maintain.