Through good times and bad, regardless of what's actually happening in the world, one thing is certain: in the long run, the Pentagon budget won't go down.

It's not that that budget has never been reduced. At pivotal moments, like the end of World War II as well as war's end in Korea and Vietnam, there were indeed temporary downturns, as there was after the Cold War ended. More recently, the Budget Control Act of 2011 threw a monkey wrench into the Pentagon's plans for funding that would go ever onward and upward by putting a cap on the money Congress could pony up for it. The remarkable thing, though, is not that such moments have occurred, but how modest and short-lived they've proved to be.

Take the current budget. It's down slightly from its peak in 2011, when it reached the highest level since World War II, but this year's budget for the Pentagon and related agencies is nothing to sneeze at. It comes in at roughly $600 billion — more than the peak year of the massive arms build-up initiated by President Ronald Reagan back in the 1980s. To put this figure in perspective: despite troop levels in Iraq and Afghanistan dropping sharply over the past eight years, the Obama administration has still managed to spend more on the Pentagon than the Bush administration did during its two terms in office.

What accounts for the Department of Defense's ability to keep a stranglehold on your tax dollars year after endless year?

Pillar one supporting that edifice: ideology.  As long as most Americans accept the notion that it is the God-given mission and right of the United States to go anywhere on the planet and do more or less anything it cares to do with its military, you won't see Pentagon spending brought under real control.  Think of this as the military corollary to American exceptionalism — or just call it the doctrine of armed exceptionalism, if you will.