Unfortunately, defense spending does not directly correlate with military effectiveness. Stephen Biddle notes that tactical proficiency is significantly more important than, and not directly related to, defense spending. Operational and strategic proficiency are even more important than tactical proficiency, and even less directly correlated to defense spending. It is also difficult to compare American military spending to other states, as the United States spends a disproportionate amount on personnel costs.

Another, and perhaps better-founded, reason for American confidence is the military’s tough, realistic training. Most of the United States’ potential adversaries do not have training centers and exercises that are as rigorous as the combat training centers, Red Flag, or several of the United States’ large-scale naval exercises. Units depart combat training center rotations more confident and prepared for deployments than when they arrived. Post-Gulf War studies say, “The results of this research, and other research as well, indicate that the realism and intensity of [combat training center] training appears to have prepared soldiers well for the ‘real thing.’” Despite their benefits, even demanding exercises are not a sure recipe for success. To take advantage of the benefits of training, militaries have to predict what combat will look like in the future — a notoriously difficult and unreliable task. Training value can only be truly measured by combat effectiveness, and combat effectiveness in future battles can’t be measured ahead of time.

This is not to say the U.S. military isn’t powerful. Large, well-equipped forces with the ability to project force globally provide a type of power that few states can rival. History, however, provides no evidence that American military power translates into genuine dominance of adversaries, leaving the comparison of conventional military power uncertain. It would be an exaggeration to say that Americans tend to enter wars as part of massive coalitions fighting against weak or exhausted enemies, then remember themselves as world champions of warfare. But it might not be as much of an exaggeration as most Americans would like to admit.