Unwinding with one of my guilty pleasures recently—Spike TV's "Ultimate Fighter" reality show—I caught a couple of recruitment ads for America's armed services with an oddly touchy-feely tone.

The first showcased the Navy's new slogan, "A Global Force for Good." "I have heard the call to serve," the narrator proclaims, and he'll carry that call close to his heart until "the anguish of those less fortunate has been soothed."

The second featured a voice-over intoning that: "Marines move toward the sounds of tyranny, injustice and despair—with the courage and resolve to silence them ... by ending conflict, instilling order and helping those who can't help themselves."

Noble sentiments, to be sure, but the War on Despair sounds even broader than the amorphous War on Terror that's consumed American blood and treasure for over a decade now. And "helping those who can't help themselves" is a far taller order than fighting "our country's battles" on air, land and sea. When did the U.S. military morph into the Peace Corps with guns?

That's something to ponder as Washington ponders yet another "humanitarian" intervention in a civil war that threatens no vital American national interest.

Last week, the usual senatorial suspects, John McCain, R-Ariz., Lindsey Graham, R-S.C., and Joe Lieberman, I-Conn.—who have rarely met a foreign war they didn't like—called for arming the Syrian opposition and launching airstrikes against Bashar al-Assad's regime.

"The only way to stop Assad's campaign of slaughter," the senators insisted, "is for the United States to take tangible steps with our friends and allies to help the Syrian opposition change the military balance of power on the ground."

Our "friends and allies" won't be much help. A confidential NATO report on the Libyan campaign, recently obtained by the New York Times, admits our European alliance partners lacked the technological capability to carry out such interventions unless the U.S. carries all the weight. American forces provided the vast bulk of some 7,000 precision-guided bombs and missiles showered on Libya during the intervention, which President Obama refused to call a "war" ("kinetic military action" was the preferred jargon).

Moreover, as American officials noted, it would be much harder to topple Assad via airstrikes than it was with Gadhafi, given Syria's superior air defenses. An attempt to stop the bloodshed in Syria could risk increasing regional chaos. As my colleague Doug Bandow points out, "Damascus possesses abundant supplies of biological and chemical weapons, including cyanide, mustard gas and sarin nerve agents. The consequences of their use by the regime and "leakage" to terrorist groups could be catastrophic."

Still, Obama's Pentagon has, somewhat reluctantly, begun contingency planning for military operations. Here we go again?

Not all of the rank and file are on board with the idea that the U.S. military should serve as the shock troops of international benevolence. A recent Navy Times article features sailors roundly mocking the "Global Force for Good" slogan: "'It sounds like a catchphrase for a bunch of superheroes,' said Chief Aviation Machinist's Mate Randy Whitney, just one of the sailors who invoked the 1970's cartoon classic 'Super Friends.' 'Do they plan on moving all the Navy's Pentagon offices to the Hall of Justice?' "

Our Constitution envisions a narrower role for the U.S. military than one that would have it responding to "trouble alerts" worldwide. U.S. armed forces exist for "the common defence ... of the United States," the better to secure the "blessings of liberty to ourselves and our posterity," as the Preamble puts it.

"Global Force for Good"? What's wrong with "Don't Tread on Me"?

Gene Healy is a vice president at the Cato Institute, the author of "The Cult of the Presidency," and a columnist at the Washington Examiner, where this article originally appeared