As a general rule, Middle Eastern regimes divide into two types: the bad—and the bad. To understand where the American interest lies in this season of Arab revolt, it’s important to know the difference.

We don’t write that in jest. The unenviable task that has confronted the Obama Administration since Tunisia’s Jasmine Revolution sent its pro-Western dictator packing in January has been to safeguard our core interests in the Middle East without betraying our core values, not the least of which is supporting local aspirations for a more liberal (in the 18th-century sense of that word) political order. In an ideal world the U.S. would not have to make that choice. But we’re talking about the Middle East, where the Obama Administration has so far been dealing with successive crises on an ad hoc basis. What it needs going forward is a strategy.

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We think that U.S. strategy should be to seek regime change among our enemies while encouraging our friends in the region to reform their domestic institutions along more liberal lines. That, in turn, requires an understanding of who our friends and foes really are—a challenge for an Administration that at times has seemed eager to blur or overlook the difference.

So it has been in recent days with Syria, whose dictator Bashar Assad was recently described by Hillary Clinton as a “reformer.” So it was, too, in April 2009, when Mrs. Clinton welcomed Moammar Gadhafi’s son Mutassim to the State Department, saying the U.S. “deeply valued” its relationship with Libya and wanted to “deepen and broaden our cooperation.”

Those are words Mrs. Clinton surely regrets today. But she could have spared herself the embarrassment had she kept more clearly in mind that the Gadhafi regime—with the blood of hundreds of Americans on its hands, its declaration of jihad against Switzerland, its capricious habit of taking foreign nationals hostage and its unabated repression of its own people—could never be a friend of the United States, whatever pragmatic concessions the West made as a reward for abandoning its WMD program.

The story is even worse with Syria, a regime the U.S. has unsuccessfully attempted to woo since Richard Nixon’s visit to Damascus in 1974. In the intervening years, the Syrians brutally occupied Lebanon for 29 years, allowed terrorist groups such as the Palestinian Hamas and the Kurdish PKK to set up headquarters in Damascus, became Iran’s principal ally in the Arab world, served as a transit center for al Qaeda terrorists en route to kill Americans in Iraq and championed the interests of Hezbollah, which itself has killed hundreds of U.S. Marines.

Then there is Iran, a regime that President Obama spent his first years in office trying to court on the theory that only the pig-headedness of his predecessor had prevented an earlier rapprochement. It took a stolen election, terrible domestic repression and endless bad faith in nuclear negotiations to persuade the Obama Administration that Iran’s hostility to the U.S. was more than Bush-deep. Yet even now Mr. Obama seems to hold out hope that some deal can be struck with Tehran over its nuclear ambitions.

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By contrast, U.S. friends in the region do not engage in this kind of behavior. This is obviously not to say that these are model countries. With the clear exceptions of Iraq and Turkey and the arguable ones of Lebanon and the Palestinian Authority, nowhere in the region are leaders elected democratically. Civil rights are enjoyed tenuously at best. Human rights are often treated with contempt. Saudi Arabia supports a vast religious establishment that preaches an extreme brand of Islam and incubates militantly anti-Semitic and anti-Western views. The list goes on.

Yet one need not be an apologist for these regimes to note that, even at their worst, Hosni Mubarak in Egypt, Ben Ali in Tunisia, or the Khalifa family in Bahrain never came close to approaching the levels of brutality routinely practiced by Gadhafi, Assad or Ahmadinejad. During the Cold War thinkers such as Jeane Kirkpatrick made the crucial distinction between autocratic regimes that were capable of a gradual process of reform and much more repressive totalitarian ones that were not—and were also inveterately hostile to the U.S. A similar distinction applies today in the Middle East.

It matters for American interests that a dictator like Yemen’s Ali Saleh has cooperated in fighting al Qaeda, that Saudi Arabia helped bolster pro-Western forces in Lebanon, that Egypt and Jordan signed and honored peace treaties with Israel, and that Qatar has contributed to the military effort against Gadhafi. These are marks of friendship that deserve reciprocal treatment.

This isn’t to say that U.S. friendship with these regimes should be uncritical or unstinting. Not least among the ironies of the current moment is that the Obama Administration’s dilemma in choosing between U.S. interests and values might have been less stark had President Bush’s freedom agenda been pressed more insistently on regimes like Mubarak’s. Much of the U.S. foreign policy establishment carped that such an agenda only got in the way of more important Mideast priorities, like the Israeli-Palestinian peace process. Mr. Bush’s vision looks largely vindicated, even if the execution of his policies was often flawed.

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Today the Obama Administration does not always have the luxury of rewinding history so that a gradual process of reform can take root. Instead, in Egypt, Tunisia, Bahrain and perhaps soon in Yemen it has been forced to make a choice between standing by friendly autocratic regimes or the people in the streets who oppose those regimes. That’s a tough call and we sympathize as the Administration maneuvers amid rapid change and new actors with often murky motivations.

The task is all the more difficult among U.S. friends, because the alternative to the current rulers can be worse. That is true in particular in Bahrain and Saudi Arabia, which are allies against Iranian imperialism and targets of radical Islamic overthrow. Preventing either is crucial to American interests in the Middle East, not least because either outcome could require the U.S. military to intervene.

The U.S. may do best here via mostly quiet diplomacy that retains its influence while encouraging reform and steering leaders away from damaging choices like Bahrain’s recent violent crackdown. Bahrain has to find a way to better accommodate the political aspirations of its Shiite majority, but the U.S. will not make that result more likely by appearing to be an unreliable friend. Likewise in Yemen, if the U.S. can’t choose with any wisdom among conflicting tribes, then it should first seek to do no harm to our ability to confront the country’s al Qaeda presence.

In Tunisia and Egypt, the dictator is gone, and the U.S now has a chance to openly promote a more stable liberal order. The Obama Administration can help liberal voices and parties organize, encourage the institutions of free markets and modern civil society, and explain the benefits of pluralism and constitutional checks and balances. We should be telling Arab publics what we are for, not merely what we oppose. At the same time, we should warn Egyptians that the likeliest result of a Muslim Brotherhood victory in elections will be less tolerance of Christians, less opportunity for women, and perhaps democracy of the one-man, one-vote, once variety.

No similar dilemma confronts the Obama Administration regarding America’s enemies. Mr. Obama may be the last to admit it, but the West has cast its lot with Libya’s rebels, and our interests lie in the swift collapse of the Gadhafi regime. What are the alternatives? A Gadhafi victory would be a disaster for NATO; an interminable civil war would be a tragedy for Libyans with spillover damage to American credibility.

U.S. interests would also be well-served by the collapse of the Assad regime, which would deprive Tehran of its major Arab client, deprive Hezbollah of one of its principal backers and save Lebanon from once again becoming a province of Greater Syria.

A successful popular uprising in Syria would also embolden Iran’s Green Movement, on whose success America’s core strategic interests in the Middle East ultimately depends. But that won’t happen until the Obama Administration openly aligns itself with that movement in the same (if often covert) way the Reagan Administration did with Poland’s Solidarity.

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U.S. foreign policy has traditionally looked with suspicion at concepts of the balance of power, and often with good reason. But as in the 1980s, the U.S. can pursue a strategy in this Arab spring that combines calculations of national interest with the promotion of freedom, a balance that marries our values and our interests. Now is the time for President Obama to pursue it.