Here’s an idea for a way the President and Congress could enforce its red line over Syria using chemical weapons without actually lobbing cruise missiles at Damascus: Congress could pass a bill authorizing President Obama to use force against Assad if he uses chemical weapons again. The goal here is to enforce the red line without actually enforcing it. It’s tough to accomplish, but it’s doable.

Let’s start by stipulating that the Administration’s goal right now is to deter Assad or any other ruler from ever using chemical weapons again. The question, then, is what is the best way to accomplish that while also looking out for our national security?

Obama has decided that only a forceful response will demonstrate to Assad that he meant it when he said chemical weapons use was a red line. But the military strategy the President has proposed was described by Secretary of State John Kerry as “unbelievably small” and would likely inflict limited damage on Assad’s capabilities. The strike would be more symbolic than anything else.

There are no good options on Syria.

The problem is that this attack has many risks and limited upside. Shooting a couple of missiles a Syria will do little to convince Assad that the United States is ready to inflict serious harm upon him if he uses chemical weapons again. The widespread disapproval of a war against Assad demonstrates this clearly. In addition, Assad could respond to such an attack with a disproportionate use of force, such as by attacking Israel, or by using chemical weapons yet again, challenging the U.S. to respond with greater military strength. Escalation is a distinct possibility. Is it worth risking destabilizing the region and possibly drawing the United State into another war in the Middle East to send a weak message?

At the same time, doing nothing indicates to Assad that his use of chemical weapons has no consequences. It’s a dangerous message to send. The Syrian leader could begin gassing his people on a wider scale, under the expectation that the U.S. will respond weakly or not at all. Since Congress has been so resistant to responding to Assad’s use of chemical weapons this time, it’s not unrealistic to think they will respond weakly to another attack as well. That’s a situation we desperately want to avoid.

As the President and Congressmen have said repeatedly, there are no good options here.

But what if Congress authorizes the President to use force in the case of another chemical weapons attack? There would have to be language in such a bill that outlined the criteria to evaluate whether chemical weapons were used and whether the Syrian government used them. It will be tricky to craft, but a combination of UN investigators (or the lack of Syrian support for them) plus government intelligence should be enough. In addition, the bill should strictly restrict the military options the President can use. It shouldn’t allow boots on the ground, for instance.

This accomplishes two things:

1. The U.S. does not have to use force right now. The vast majority of Americans and Congress don’t want to use force. The risks are simply too high and benefits too low. By passing an AUMF for a future chemical weapons attack, it makes sure we do not use force right now.
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2. At the same time, it deters Assad from using chemical weapons again. It’s not the strongest form of deterrence, as it still informs Assad that the consequence of him using chemical weapons will be limited in scope. But it is much more of a deterrent than doing nothing. Obama should also make clear that he will go back to Congress for the authorization to use greater military force if he deems Assad’s transgression consequential enough to require a stronger U.S. response.

Is this a weak response? Absolutely. But every response being contemplated is weak.

Here’s a pessimistic scenario: let’s say such a bill is passed and Assad takes it to mean that he can gas a number of Syrian civilians and expect a limited response. He goes ahead and does so and the President responds by following through on the AUMF. He goes back to Congress to ask for more military options, but is shot down again, confirming Assad’s belief that the U.S. doesn’t want to get too involved in Syria. That’s a bad outcome.

But look at how that scenario plays out if we do nothing now: Assad sees no U.S. response and believes that America will not respond (or will respond weakly) if he gasses his civilians again. Now, Obama asks Congress for the right to use military force. Maybe they give it to him now, but at best it restricts him to limited strikes anyways. If the U.S. doesn’t respond this time, it signals to Assad clearly that the U.S. is a paper tiger over chemical weapons use. That’s a huge risk. Passing the bill I’ve proposed at least eliminates this possibility.

And what about if we strike Syria now? Well that certainly acts as a greater deterrent to Assad, but as I’ve already noted, the risks involved in this are too high to go through with it.

This is a way to credibly deter Assad without the risks of using force. Assad will know with certainty that if he uses chemical weapons again, Obama will respond with military force. That may not be a strong enough deterrent, but it’s better than nothing in a world where there are no good options.