Liberals eyes roll back in their heads when they hear conservatives oppose defense cuts.The Post’s Matt Miller is typical, insisting we can do national security on the cheap and accusing hawks of being part of a “cult.” But the analysis is inane. To compare our defense budget to Iran (we have, you see, different national security objectives), or to say we spend more than we did in the past is to ignore the real issue: Are we spending what our current and future national security demands require? Honest defense cutters are candid enough to say that they simply want to retreat to fortress America, regardless of the impact on our overseas commitments.

Miller would no doubt consider House Armed Services Chairman Buck McKeon a cultist. But his analysis on the impact of budget cuts on our ability to meet our current and future national security needs is hard to dispute. (Miller doesn’t try.)

McKeon in the Wall Street Journal today offers these observations:

Since then-Defense Secretary Robert Gates launched an “efficiency” campaign in 2009, we have cut over half a trillion dollars from our armed forces. Although defense spending accounts for less than 20% of our federal budget, it has absorbed approximately half of our deficit-reduction efforts since 2009.

Now the super committee is operating under a mandate that holds our military hostage. If the 12 members don’t agree on $1 trillion in cuts from the vast federal budget, an automatic “trigger” will cut $500 million from defense along with $500 million from elsewhere.

Such a drastic cut would force the Navy to mothball over 60 ships, including two of our precious 11 carrier battle groups, according to analysis by the Republican staff of the House Armed Services Committee. It would also force us to shed one-third of our Army maneuver battalions and Air Force fighter jets.

The Marine Corps, meanwhile, would have to rewrite its warfighting doctrine and re-evaluate its core mission. The Corps already has too few ships to keep Marines at sea. . . .

These radical changes would significantly degrade, if not eliminate, our ability to fulfill our commitments to allies like Taiwan and Israel. When asked by a Senate committee if the super committee’s trigger would be “shooting ourselves in the foot,” newly minted Defense Secretary Leon Panetta quipped: “We’d be shooting ourselves in the head.”

I suppose Panetta is part of the cult too. McKeon also dismisses the country-by-country comparison. “It costs exponentially more money to sustain a U.S. service member than to keep a Chinese, Iranian or North Korean soldier under arms.” Put differently, it costs a lot more money to defend against the host of threats we face than is does for the rogue states to kill Americans, disrupt trade and imperil our allies.

There is also the economic rationale against defense cuts. As McKeon says: “The U.S. military is the principal guardian of our globalized economy’s avenues of commerce. We protect the realms where business occurs and prosperity is born, including space, the skies, cyberspace and the world’s oceans.” Most directly, he reminds us that “if the super committee fails to reach an agreement, its automatic cuts would kill upwards of 800,000 active-duty, civilian and industrial American jobs.”

But let’s be clear: The purpose of the defense budget is to defend the country, not to serve a a jobs program. All defense cuts and increases should have a national security rationale. Unless they do, it is irresponsible to propose them. And if we want to cut the debt then, as McKeon argues, we should look at “the real drivers of our debt, namely entitlements and social welfare, not on the protector of our prosperity.”