As Gregg Easterbrook describes in Sonic Boom, "Military spending is among the least desirable uses of social resources. The best-case outcome for most defense spending is that it is totally wasted - that is, military force is never used. Worst-case outcomes go downhill from there."
So what's the good news? He continues: "As most nations have begun spirited economic competition, they have reduced their competition in arms buildups. Stated in today's dollars, global military spending peaked in 1985 at $1.5 trillion, and by 2008 had fallen to $1.3 trillion. Owing to world population growth through the period, military spending has declined from $312 per capita in 1985 (in today's dollars) to $194 per capita in 2008."
Source: Sonic Boom, p. xv.