Reps. Randy Forbes (R-VA), Michael Turner (R-OH), Rob Bishop (R-UT) and Mike Conaway (R-TX) are anxious to fend off cuts in military spending. Writing in Politico, they admit that our military is second-to-none, "but the strength of our armed forces should not be taken for granted." The four call for "sustained investments in our troops and their equipment" to avert a hollowing out of U.S. military power. They repeat the tired claims that the Obama administration has "executed two rounds of defense cuts" (Truth: military spending continues to rise, as I noted here last week) and they close with reliable flag-waving rhetoric about Congress's patriotic duty to "to do its job and provide adequately for the common defense."

The timing of the Forbes et al cri de coeur is predictable: momentum is building for actual cuts as even a number of conservative Republicans have come forward with specific plans (see here and here).

The small and shrinking band of military spending advocates, meanwhile, sticks to a clear and simple message. Every problem in the world, no matter how distant, is the responsibility of the U.S. taxpayer, and our brave men and women in uniform to fix. The threats facing us are great, and growing. And they conflate spending to advance U.S. security—a clear constitutional obligation for all members of Congress—with what our military actually spends most of its time doing: defending other countries that can and should defend themselves.

In other words, the "common defense" that Forbes, Turner, Bishop and Conaway aim to uphold applies to every person, in every country, on Earth. They propose to extend the rights of American citizens to several billion people who are not parties to our social contract. And they expect that American taxpayers will happily go along, continuing to foot the bill while everyone else enjoys the benefits.

This is a fool's errand. Americans have long chafed at bearing the burdens of global governance, and they are understandably interested in a new compact with the world as the debt crisis deepens. They want fewer wars, less military spending and more burden-sharing by allies.

Contrast Forbes et al's overheated rhetoric that America is in danger of losing our military edge, and their stubborn insistence that Americans should bear the burdens of defending the world, with Richard Haass's even-handed assessment of the foreign policy challenges that the United States is likely to face in the coming decades. The threats, Haass shows, are modest and manageable, and they allow for a more discriminating approach to U.S. intervention abroad.

"The biggest external threats confronting the U.S.," Haass explains, including "the spread of nuclear materials and weapons, the possibility of pandemic disease, climate change, [and] a breakdown in the functioning of the world's financial and trade systems" are not susceptible to military solutions.

Haass, the president of the Council on Foreign Relations and a senior foreign policy adviser to both Presidents Bush 41 and Bush 43, can't be dismissed as a flak for progressives and peaceniks. I don't endorse everything that Haass proclaims in this article (for more on that see here), but his assessment of the threats facing the United States is fundamentally correct. If Washington were to embrace his reasoning, it would allow for a prudent and responsible reduction in military spending that does not undermine U.S. national security. On the contrary, modest reductions on the order of 10-15 percent of projected Pentagon spending over the next decade (between $600 billion and $900 billion), if combined with other fiscal reforms and spending cuts, could help put the country on a sustainable long-term path.

Reps. Forbes et al might believe that they can convince their fellows in Congress to declare more than 50 percent of the discretionary budget off limits, but the wiser course would be to read the handwriting on the wall, recognize that the Pentagon's budget will eventually come down, and begin a serious discussion about the purpose of U.S. power. If they are worried about the strains being placed on our military, they should be proposing ways to shed and shift some of the burdens of "the common defense" to other countries.