Discussion of the “fiscal cliff” since the presidential election has focused so far on the type and amount of tax increases that congressional Republicans might accept and the changes in entitlement programs that President Obama and Democrats could agree to in exchange. Sooner or later, however, the negotiations must turn to the crucial subject of defense spending. The automatic spending cuts due to kick in at the beginning of next year include $56.5 billion from the Pentagon, more than 10 percent of its base budget. If left unchanged, the sequester would cut defense by $454 billion over a decade.