In 1919, flush with victory in World War I but bled white from the fighting, Britain’s government announced a “ten-year rule” in its defense planning, premised on the expectation that the country would face neither a major conflict nor the need for a large overseas deployment for at least a decade.1 That decision freed Britain to slice defense expenditures and maintain only a skeletal defense force, an adequate navy, and some capability for colonial policing. The rule remained in effect until late 1932, shortly before Hitler’s appointment as German chancellor. Seven years later, Britain was at war, and within eight was fighting for its life against the German Luftwaffe.
Since that time, enthusiasm in the United States for a similar rule has been tepid at best. During the Cold War, it would have been out of the question, but a decade after the conclusion of that competition the idea remains anathema to American military and strategic planners. Readiness is the mantra of the armed services and the touchstone of presidential politics on military issues. Few people, however, have stopped to ask whether the enemies that the U.S. military is now ready to face resemble the likely enemies of the future. The simple answer is that they may not.