In the last year, President Obama loudly denounced Syria dictator Bashar al-Assad for human rights abuses and confidently predicted the regime’s fall. But as in virtually every other difficult foreign policy question, the president has preferred to “lead from behind,” which in this case means doing absolutely nothing while Assad slaughters thousands. The most recent Syrian atrocity has brought this shameful inaction back into the spotlight, but as Mitt Romney’s justified criticism of Obama on the issue yesterday makes clear, both the president and his challenger need to come up with more coherent positions.

The administration has tried to have it both ways on Syria ever since the protests there began more than a year ago. On the one hand, Obama wants to pose as the scourge of tyrants and a supporter of human rights, so he has claimed it was only a matter of time before Assad was driven out. But he has done nothing to match those words, and the result is that the atrocities continue with no end in sight. Romney rightly criticized this inaction yesterday as an example of the president’s feckless and cowardly foreign policy. But though this critique is warranted, Romney’s own prescription for U.S. action on Syria isn’t a heckuva lot better. As the New York Times reports:

He called for the United States to “work with partners to organize and arm Syrian opposition groups so they can defend themselves” — a policy that goes somewhat further than Mr. Obama’s but falls short of the airstrikes advocated by Republicans like Senators John McCain of Arizona and Lindsey Graham of South Carolina.

The problem here is that despite the blithe assumptions commonly heard in the West about Assad’s inevitable doom, there is no reason to believe that he cannot sustain himself in power so long as the security services remain loyal to him.

Having already killed so many of his countrymen, why would having a few hundred more corpses do him in when he hasn’t been toppled despite the thousands already slain? The iron law of history teaches us that tyrannies fall when they weaken or lose their willingness to shed blood and not before. The material support Assad is getting from his ally Iran and their Hezbollah auxiliaries have helped offset any harm incurred by Western sanctions, which are largely meaningless because of the limited scope of trade with Syria.

The only thing that will put an end to Assad’s reign of terror is Western military intervention or direct aid to the Syrian rebels. There are, as the White House has pointed out, good reasons to worry about arming the Syrian opposition. As a top-ranking Israeli military official pointed out today, should Assad fall, elements of al-Qaeda that may be sympathetic to the opposition in Syria could be empowered or at least be given free reign to conduct terror operations against Israel or the West.

The Times is right to point out that few in this country on either side of the political aisle are eager for another foreign adventure, even one that really would be a matter of saving thousands of lives. There is also good reason to believe that intervention in Syria would not be as easy as last year’s European-led effort to oust Muammar Qaddafi in Libya. But that is no excuse for standing by while hundreds, if not thousands are slaughtered in Syria by Assad, while Western leaders like Obama preen ineffectually about their support for human rights.

The analogy to Libya also breaks down because the stakes in Syria are far higher. The atrocities in Syria dwarf those in Libya. It should also be pointed out that toppling the Assad regime would be a telling blow to Iran and its terrorist allies. Though we don’t know what a post-Assad Syria would look like, in the long run, regime change there would be good for the region as well as the Syrian people.

Absent a commitment to take action, nothing Obama or Romney says about Syria has much credibility. It may be too much to expect either man to embrace the possibility of armed conflict in Syria, but anything less will not solve the crisis.