Cliff May of the Foundation for Defense of Democracies writes in response to some conservatives’ qualms about U.S. action to help topple Bashar al-Assad:

[I]t should become apparent that the threat posed by Iran is more urgent, by an order of magnitude, than any other now on the horizon. The War against the West that began with Iran’s 1979 revolution, from which have sprung all the other modern Islamist and Jihadist movements (al-Qaeda’s very much included) will be won or lost — it is not a misunderstanding that can be resolved through “confidence-building measures.” That ought to prompt us to ask: What is our war-fighting strategy? On which battlefields must we engage our enemies? Which battles must we win?

The answer to these questions — not frustration with the dearth of sincere Muslim freedom fighters, justified though that is; not humanitarian concerns, laudable as those may be — should determine whether or not we provide material assistance to the Syrian opposition.

And that’s all we’re talking about here: Those facing Assad’s guns are not asking us to put boots on the ground. What they do want are the means to defend themselves, secure communications technology, and a limited number of other assets that will give them a fighting chance — though no guarantees. Providing such assistance will give us a fighting chance to influence the opposition now and the post-Assad environment later — though no guarantees.

The alternative is to stay on the sidelines, leaving the opposition to the tender mercies of Assad and his patrons in Tehran who are supplying weapons, advisers, and more. They grasp that the Battle of Syria is hugely consequential. They know that the fall of Assad would be a major blow to them. By the same token, it will be a major blow to the West if, despite Washington’s pronouncements and posturing, Khamenei, with assistance from the Kremlin, rescues and restores his most valued Arab bridgehead. And should Khamenei move from that victory to the production of nuclear weapons, we’re in for a very rough 21st century.

This debate goes to the heart of my concern for a more systematic and fact-based approach to human rights and democracy promotion.

In a real sense, Syria is the best case for U.S. action. Going through some of the criteria I previously discussed: We can (and must, if we want to do anything) act outside the United Nations, but with bilateral and regional allies. In May’s plan, we would be primarily acting to support the Syrian opposition, which would do the heavy lifting. And most important, we have critical strategic interests at stake.

Nevertheless, because the United States has failed to devise a clear policy to assure war-weary Americans that its leaders can differentiate between situations necessitating our action and those which don’t and because those leaders have been half-hearted in cultivating nonmilitary options, I understand the qualms of many who fear an endless parade of military incursions.

“Good fences make good neighbors,” wrote Robert Frost. But good fences — policy limits achieved by rigorous thinking and a realistic assessment of our interests and options — also make good policies. Promoters of human rights and democracy need some well-constructed fences, or their efforts to project American values in support of a freer, more peaceful world won’t be sustainable over the long haul.