When a story gets as much attention as the poison gas attacks in Syria, it’s hard to separate what we know from what we think we know.

Regarding Syria, here’s what we know: Canisters of poison gas opened around Damascus, killing about 1,000 people on Aug. 21. That’s it.

Was it delivered by rockets? Maybe. Was it sent by the regime of Bashar al-Assad? Could be, but there is a good case to be made that it came from another party in a multi-faceted civil war.

Even less is clear about the United States’ planned response of using — according to what look like deliberate leaks — cruise missiles to punish the regime without putting American lives at risk.

Would it work? Maybe. Will it change the balance of power in the Syrian war? Probably not.

Will it drag us into another war in the Middle East? Who knows?

Those are the kinds of questions members of Congress should be asking before they authorize President Obama to use force, and if they don’t get better answers than those above, their answer should be no. The stakes are too high.

William Polk, a historian and foreign policy expert, has written a thorough analysis of what’s been reported from Syria in an article posted on The Atlantic magazine’s website.

It is hardly the “beyond a reasonable doubt” case that Secretary of State John Kerry was describing Tuesday.

Syria, like many countries, likely has stores of poison gas and it has a history of using it. But Polk raises the crucial flaw in the theory that the Assad regime would use a gas attack now. It has much to lose and almost nothing to gain.

Gas is a terrifying weapon, but not much use in guerrilla war, Polk observes. The rebels are hidden and dispersed. A gas attack in a neighborhood is unlikely to catch many of them. The timing is also strange. The government has reportedly been succeeding recently in prosecuting its war with conventional means.

Using gas would bring the U.S. military in, especially after the president called it a “red line” Syria should not cross.

The rebels, on the other hand, have more to gain. They represent a broad spectrum of groups, religious and secular, Syrian and foreign, with conflicting interests. There is even an al-Qaida faction in the resistance, which is why the administration did not want to arm them earlier this year.

A group like that would have the most to gain from an attack that brought the U.S. into the fight. But even if the case against Assad is ironclad, there questions about whether an air strike or two would make any difference. What if after the airstrikes, the Syrians do it again? How far would the escalation go? How long are we ready to stay with this strategy?

An editorial in the German daily Handelsblatt (also published in The Atlantic) raised the question of American commitment which is crucial to this decision.

“Humanitarian wars are also wars,” it says. “Those who jump into them for moral reasons should also want to win them … There has to be a strategic motivation behind the moral one, and (winning) demands perseverance.”

The best argument that the pro-intervention side has is that we have a moral imperative to act.

If you can do something that can prevent suffering, you have an obligation to do it. Doing nothing is just allowing the suffering to continue, so doing nothing is doing something, too.

But this is a trap. Believing that our force is so powerful that we could change the course of a war with no cost to ourselves besides money is a dangerous illusion. If we want to tell all other countries and terror groups that using poison gas will bring terrible consequences, it will take more than a few cruise missiles fired from a ship at a safe distance to do the job.

Poison gas is a terrible weapon, but it only represents 1 percent of the deaths in Syria over the last two years. Escalating the civil war with outside intervention could lead to more killing with all the available weapons.

A vote against this intervention would not be a vote for poison gas, it would be a vote against stumbling into another foreign war.

After what this country has experienced over the last decade, that is something we all should understand very well.

Greg Kesich is the editorial page editor. He can be contacted at 791-6481 or at:

gkesich@pressherald.com