Late last year, I interviewed Bernie Sanders while working on my biography "Bernie." I asked him if he planned to reduce the defense budget if elected president. "We will take a hard look at that," he told me, agreeing that there's an awful lot of bloat in America's military spending that ought to be cut.

Why doesn't he say that now?

A statement detailing his intent to reduce military spending — not just the on-the-books budget of the Pentagon, but also the "off the books" tax dollars that go to wars like the occupations of Afghanistan and Iraq, as well as the National Security Agency and other parts of the surveillance state that have expanded radically since 9/11 — would help answer one of Sanders' critics' most potent criticisms: that he'll be an irresponsible Santa Gone Wild, giving away free college tuition and Medicare for all without a care in the world for how to pay for it.