We already knew the Tea Party scared liberals to death, but it seems the movement also terrifies liberals’ nearest cousins, the neoconservatives, on an issue dear to their bellicose little hearts: foreign policy.

Bush-speechwriter-turned-Washington-Post-columnist Michael Gerson warns that the Tea Party’s ascendancy could have “the scariest kind of influence on America’s role in the world: massive and unclear.” It might even turn against our endless nation-building adventure in Afghanistan!

Also in the Post, American Enterprise Institute analysts Danielle Pletka and Thomas Donnelly worry that “American international leadership” is threatened by “an almost Calvinistic call to fiscal discipline,” with Rep. Ron Paul, R‑Texas, and Sens. Rand Paul, R‑Ky., and Tom Coburn, R‑Okla., leading the ascetic elect.

Color me skeptical: I’m not convinced that the TP’ers plan to pry us loose from our outdated and dangerous “entangling alliances” and downsize our bloated Pentagon budget, very little of which can fairly be classified as “defense.”

I am convinced that’s what they should support if they mean what they say about limited, constitutional government.

Near as I can tell, the TP’ers don’t care much about foreign policy. In the largest national survey of movement supporters, April’s New York Times/CBS News poll, vanishingly small numbers put Iraq, Afghanistan or terrorism at the top of their concerns.

The GOP isn’t yet feeling any pressure to rethink the Afghan War. A Nov. 4 National Journal graphic ranks Afghanistan as the most likely area for “outright cooperation” between Obama and the new House majority.

So why the handwringing? Neocons tend to see danger everywhere, turning every tinpot dictator with a mustache into the next Hitler. Maybe this is another case of hysterical hypersensitivity to perceived threats.

Or maybe not. For the first time in a decade, there are tentative yet hopeful signs of new thinking in conservative defense policy.

Last week, a group of movement leaders, including Grover Norquist, Brent Bozell and Al Regnery, issued an open letter to the GOP leadership urging “no sacred cows” in spending reform: “Department of Defense favoritism would signal that the new Congress is not serious about fiscal responsibility.”

The Politico reports that in his quest to cancel some weapons programs, Secretary of Defense Robert Gates “may get help from an unexpected ally — the Tea Party movement.”

Let’s hope so. Pletka and Donnelly argue that defense costs “only” 4.9 percent of GDP a year. (I suppose Medicare and Medicaid — at just over 5 percent — are a bargain as well.) But that slice of the federal budget — 23 percent and counting — has proved historically to be one of the easier areas to cut.

Under Clinton and the Gingrich Congress, the post-Cold-War peace dividend contributed mightily to the era’s budget surpluses.

And as a few Republicans on the Hill are starting to recognize, it’s well past time to draw down in Iraq and Afghanistan. As the American Spectator’s Jim Antle observes, “we will not be able to fight the neoconservatives’ wars with the supply-siders’ tax rates.”

Our Founders recognized that realism and restraint ought to shape the foreign policy of a constitutional republic. Abandoning that restraint hasn’t quite brought the warm glow of “national greatness” the neoconservatives promised.

Eight years of off-budget wars and dubious nation-building schemes have brought staggering costs in blood, treasure and diminished national prestige.

In an article posted Saturday, the New Republic — ong the home for crusading liberal hawks — claims that “the Tea Party is wrecking Republican foreign policy.” It’s not at all clear that the Tea Party movement has that ambition. But the establishment GOP’s foreign policy has caused wreckage enough already.