As US President Barack Obama ponders whether to send an additional 40,000+ American troops to Afghanistan, the bigger question is whether the US really has enough troops to neutralise its enemies.

The US has a demonstrable ability to defeat conventional military forces in places such as Iraq (1991, 2003), Serbia (1999) and Afghanistan (2001), but has run into major difficulties pacifying occupied territory thereafter. Insurgencies in Iraq and Afghanistan have proved very costly to the US. Some 5,200 American troops have been killed there so far – much fewer than the 58,000 killed in Vietnam, but still substantial.

Iraq appears to have calmed down (although the weekend’s massive bomb blasts in Baghdad demonstrate the fragility of the country’s peace), but Afghanistan is hotting up. The US has about 120,000 troops in Iraq, and almost 68,000 in Afghanistan, which could rise to 108,000 if Obama meets Afghan theatre commander General Stanley McChrystal’s extra troop request.

But even 108,000 American and 40,000 other Western troops may not be enough to pacify Afghanistan, even with the support of 170,000 Afghan National Army (90,000) and police (80,000) forces. The Soviet Union deployed 115,000 troops with the support of the 300,000-strong Afghan military and failed to fully control the country. Furthermore, Afghanistan’s population has almost doubled since the 1980s, meaning that even if the West were to match the Soviet-Afghan troop total, their per capita force would be far smaller.

Some Estimates Say 600,000 Troops Needed In Afghanistan

According to various US military studies, stabilising a region experiencing a counterinsurgency requires 20-25 military or police personnel per 1,000 local citizens (see page 109 of a new book, The Science of War by Michael O’Hanlon, to be reviewed on Risk Watchdog soon; see also this extensive paper on counterinsurgency by the US military). Based on this ratio, and assuming an Afghan population of 30 million, the West and the Afghan government would need 600,000-750,000 military and police forces to maintain order. Even if Afghan forces were to be increased to 400,000 as some advocate, this would take several more years, and 200,000-350,000 Western troops would be still be needed – more in fact, since Afghanistan’s population will continue to increase.

The US had 1.465 million personnel at the end of August 2009, but is already stretched by its existing global commitments. Deploying hundreds of thousands more troops to Afghanistan would probably require the restoration of conscription, which would be political suicide for any US president. In the absence of a new world war, I cannot see how the US would reinstate the draft.

Afghanistan Could Constrain The US From Dealing With Other Threats

Thus far, I have only discussed Afghanistan; I have not even mentioned circumstances in which Pakistan or North Korea collapses, the US attacks Iran, Mexico’s drug wars start spilling across the US border, or Russia attacks Georgia again.

Admittedly, these things are highly unlikely to happen all at the same time. However, none is beyond the realm of possibility. According to O’Hanlon, around 1 million to 3 million foreign troops would be needed to stabilise Pakistan, and it is unclear to me who would be willing to provide these. As for North Korea, stabilisation efforts there could be taken care of by the South’s 650,000+ troops assisted by remnants of the North’s military and possibly by a Chinese military presence, so the US has less to worry about there. However, a ground war against Iran, forays into Mexico, or a build-up in Georgia to deter possible aggressive moves by Russia could stretch the US military towards breaking point.

So in summary, Obama’s real dilemma is not whether to send 40,000 more troops to Afghanistan; rather he must decide whether the US needs to expand its military substantially so that it can deal with several very real scenarios at the same time. Realistically, America’s 10% of GDP fiscal deficit means that the money simply isn’t there. In addition, the US has had difficulty meeting recruitment targets. The Pentagon recently revealed that rising unemployment has allowed the military to meet all its recruitment goals in the past fiscal year for the first time since it became an all-volunteer force in 1973.

However, if money were less of a constraint, and absent the restoration of the draft, there are two ways in which the US could boost its troop strength. Firstly, the US could seek to recruit military personnel directly from poor, underdeveloped countries with promises of citizenship in return for military service. Secondly, it could accelerate the use of robotic combat platforms, as adumbrated in a recent book, Wired For War: The Robotics Revolution and Conflict in the 21^st Century (another one I hope to review on this blog soon) – although the technology for this is likely to be decades away. Either solution would substantially transform the US military and have substantial political implications.

There is a third option: disengage from Afghanistan and Iraq, and concentrate on defending Fortress North America. However, this might be interpreted as defeat, thereby undermining US prestige.