Libertarian foreign policy can be summed up in one word. No, the one word is not Isolationism, accompanied by a cartoon of Ozzy the Ostrich with his head planted in a sand trap. The word is Noninterventionist, accompanied by a cartoon of Iggy the Eagle with an olive branch in one claw and a nuke in the other.

The sole justification for U.S. military might is to protect Us from Them. Period. End of story. We are not world cops, not world nation-builders, not world democracy-makers, not world sugar daddies.

So far, libertarians agree. But libertarianism is not a shapeless muumuu. One size definitely does not fit all. An issue where libertarians diverge is surveillance. When our recon plane took unscheduled leave time on Hainan Island libertarians of every stripe and type checked in with opinions ranging from "An apology to China Is long overdue" (LewRockwell.com) to "China should release the crew immediately and apologize " (Ted Galen Carpenter, Cato Institute).

The price of freedom, spake Thom. Jefferson, is eternal vigilance, and that includes military surveillance.

Forget historical revisionism for a moment and pretend that Pearl Harbor really was a completely unknown, unexpected, never-had-a-clue sneak attack. Do we ever want that to happen again? Especially in today's age of hydra-headed missiles and tomorrow's orbit-launched killer-zapper energy shazams?

By surveillance I don't mean sending a trench-coated Boris Badenov type into somebody else's bailiwick to skulk about in cloak rooms and bed chambers and such. Except in times of declared hostilities, spying is trespassing at the least and outright thievery at the worst. Master spy guys claim that the best dirt is gathered by human snoops on the ground. But I strongly suspect that we learn more from a single high-placed defector. So first we should make ourselves the freest society on Earth by readopting the Constitution and then openly advertising for defectors:

Calling All Top Aides of Marxist Socialist Commie Pinko Fascist Despotic Tyrants! Want Freedom, Security, and American cheeseburgers? Trade Your Warmonger's Most Intimate Secrets for American Citizenship! Defect Today! Try it! You'll like it!

Surveillance means crowning a few obvious candidates as Most Likely To Do Us Grievous Harm and then tracking them with every noninterventionist doodad in Batman's utility belt. Aircraft in international airspace. Subs in the open seas and ships beyond territorial limits. Satellites in space. And then invite them to do the same to us. What does a free country have to hide, a military force that makes us the windshield and them the bug? Instead of Mutually Assured Destruction we'll have Reciprocally Understood Military Potential. At least the acronym would be more fun than MAD.

Surveillance also means all manner of electronic eavesdropping. Unfortunately, granting our government the power to snoop on others is an open invitation for them to snoop on us, and there goes our privacy. So let's pause and mull this one over.

What is today's justification for Americans spying on Americans? Fighting the drug war? The drug war is blatantly unconstitutional. Stop the war and you stop the justification for spying. Combating criminals? Wipe the slate clean of all victimless crimes and you stop most of the justification for spying. Anti-terrorism? We create anti-American terrorists by our own arrogant agenda of micromanaging every sand and jungle country in the Rand McNally International Atlas. Butt out of everyone's business and they'll get their hairy butts out of ours. Electronic monitoring is a danger to Americans only because our government is a danger to Americans. The answer is to make our government obey the Constitution. And isn't that, after all, the whole point of the libertarian movement anyway?

Another ingredient in the Aggressively Peaceful strategy is being aggressively diplomatic.

Example One. Hutus and Tutsis are very bad neighbors. They periodically treat one another to genocide. Horrific? Absolutely. Does it threaten to spill over onto American soil? No. Conclusion: not our business. Example Two. India and Pakistan are very bad neighbors and they both have nukes. While a nuke-swapping party would be horrific it still isn't America's business. But what about the fallout? Could the jet stream pick up the resulting cloud of death and dump it on American picnickers? That makes it our business, and calls for a strong dose of diplomacy. Sound callus? Maybe. But our Constitutional mandate is to protect American lives. Attempting to protect everybody from everybody is unconstitutional. Funding the attempt turns every American citizen into a tax slave, also unconstitutional.

Selective defense. Rewarded defection. Open mutual surveillance. Aggressive diplomacy. No covert spying. There's your libertarian noninterventionism.