Measuring Military Power: You're Doing It Wrong

True net assessment is a lost art these days, at least in popular military budget discussions. Let's take this Bloomberg piece, for example. First, the headline: "Obama's 'Paper Tiger' Pentagon Budget Spends Five Times China." I understand and respect that the piece is mostly about rebutting an election year claim that reductions of the defense budget will make the US militarily weak. I have no desire to wade into those muddy waters since they have been well-covered by others. But, as the article title implies, the piece supposedly rebuts the claim by looking at the data:

U.S. spending accounted for 41 percent of global military
expenditures in 2011, according to the Stockholm International
Peace Research Institute. China accounted for 8.2 percent and
Russia 4.1 percent, the Stockholm-based policy group said in an
April report.

And this is where the problem begins. It means nothing to state that the US outspends China by five times because flat aggregate comparisons of defense spending tells us little about operational and strategic outcomes. Let's start with the strictly material: The US is a global power with global responsibilities. China, on the other hand, regionally concentrates its forces. The US is operating at the periphery whereas China, an power rooted in the hard crust of the Asian landmass, has no such logistical problems. Such a figure also tells us nothing about the correlation of forces in the theater in question, or whether each power has managed to translate spending into usable military resources. Given that there have been a lot of news stories about whether or not the US has been getting value out of its latest aerial platforms and problems associated with aging Cold War-era systems as well as the way that personnel and per-unit major platform costs may be causing a "defense death spiral," such an omission has analytical consequences.

Doctrine and force employment matter too. During the late 70s, Phillip Karber ran a simulation of May 1940 for an overly quantitative theater balance methodology called WEI-WUV and found that it didn't account for French and British defeat. The Allies may have enjoyed quantitative and qualitative platform advantages but did not master the "modern system" of military operations that had evolved out of World War I. The Germans, on the other hand, were farther along in the path towards combined arms mobile warfare even if they had some serious material and doctrinal flaws of their own. Andrew Marshall also reminds us that the socio-bureaucratic set of relationships within a military hierarchy also have an impact on effectiveness.

Finally, let's go to the most important factor: the human. WJ Rue at Gunpowder and Lead explains:

Let’s assume that the U.S. and Russia spend the same amount of money on
their respective militaries. Let’s further assume that the U.S.
allocates a sizeable portion of its resources to training – we’ll say
the average fighter pilot gets roughly 150 hours per year in the
cockpit. Russia, meanwhile, elects to spend its resources on slightly
more capable jets, but its pilots only get 20 hours per year flight
time, and they ran out of money before they could build a simulator. If
we assume that similar circumstances exist throughout the Russian armed
forces, who has the more capable military? The well-trained one or the
one with the expensive equipment that the troops don’t know how to use
effectively?

Is it too much to expect this in a short piece ostensibly about US budget debates and election politics? Probably. But defense budget debates are also never served well by using total military spending as a good metric of comparison of military power. As Rue argues, military power has aspects that are easy to quantify and other facets that are difficult to express on a balance sheet. Hence, the utility of net assessment.