For all you innumerable skeptics of President Obama’s calls for military strikes on Syria, consider this:For decades, Syria has refused to confirm that it has chemical weapons. Now, facing a limited strike, its position abruptly changed to: Oh! We do have them after all! And we want to sign the Chemical Weapons Convention! We want to show them to United Nations inspectors.

In short, the mere flexing of military power worked — initially and tentatively. And while it seems that neither Congress nor the public has any appetite for cruise missile strikes on Syria, it will be critical to keep the military option alive in the coming weeks or Russia and Syria will play us like a yo-yo.

Frankly, I’m skeptical that a deal can be worked out in which Syria hands over its chemical weaponry, and President Obama may have exchanged a losing struggle with Congress with a Sisyphean struggle with Russia. But it’s not impossible. And even if Syria cheated and stalled and eventually handed over only half of its chemical arsenal and none of its biological arsenal, that would still be a huge win for global security.

So here’s a three-track strategy for Syria going forward:• Negotiate with Moscow on removal of Syrian chemical weapons and insist on conditions to ensure we’re not being played, including immediate disclosure to the United Nations of chemical weapons stockpiles, a binding Security Council resolution confirming the deal, a reference in the resolution to “serious consequences” for noncompliance, and immediate installation of camera monitors on at least a few locations.

• Groundwork in Congress to authorize a limited missile strike if Syria does not comply, partly to retain leverage with Moscow.

• Expansion of efforts to arm and support moderate Syrian rebels, accompanied by covert cyberwarfare on the Syrian regime, to try to change the momentum on the ground.

Ultimately, that’s the best hope to coerce President Bashar al-Assad to step down so that all sides can try to reach a cease-fire and power-sharing agreement. Yet if we’re going to sustain the pressure, we have to address these fundamental questions: Can we really promote peace with military force? Is it possible to help a country by bombing it?Longtime readers know that I adamantly opposed the Iraq war and Afghan surge, oppose strikes on Iranian nuclear sites and tend to think we overinvest in military tools and underinvest in diplomatic ones. So many readers were stunned that I’ve endorsed missile strikes on Syria — and I’m hearing screams of betrayal.

“You can’t kill people to show that it’s wrong to kill people,” Christine protested on my Facebook page.

“When has violence, killing and aggression helped anything,” demanded Jan, also on Facebook.

The answer is: Sierra Leone, Mali, Ivory Coast, Bosnia and Kosovo. In each of those countries, an outside military force intervened at minimal cost and saved large numbers of lives. In several (as Clausewitz would have predicted), war buttressed diplomacy and helped achieve peace agreements.

We think of warfare in binary terms, as if our options are invasions or nothing at all, but that’s misleading. All-out wars have a poor record, but modest interventions of the kind President Obama is talking about in Syria have a more successful (though still mixed) history.

That’s even true in Iraq, although I hate to mention the word because it sends a shudder up every reader’s spine. While the war that began in 2003 was a disaster, two limited interventions succeeded in Iraq. One was President Clinton’s 1998 bombing of Iraqi military sites for a few days (maybe the closest parallel to Obama’s plan for Syria); it may have convinced Saddam Hussein to abandon W.M.D. programs. The other is the no-fly zone over Iraq’s Kurdish areas in the 1990s to prevent a genocide there. They were limited uses of force that proceeded so smoothly that they are hardly remembered.

“War is obviously terrible, but it’s not the ultimate evil,” notes Kenneth Roth, executive director of Human Rights Watch. “Some things are worse, and one is the deliberate slaughter of civilians.”Human Rights Watch doesn’t take a position on a strike on Syria, and Roth notes that military intervention isn’t the first tool to reach for to prevent mass atrocities. Sometimes armed intervention hurts. Sometimes it helps. We’re left to decide on a case-by-case basis.

In Syria, for two-and-a-half years, we’ve given the regime a green light, and the killing has escalated from 5,000 a year to 5,000 a month — and, last month, to a poison gas attack that was perhaps the biggest massacre in the war. Now Obama’s threat of military strikes has turned the light yellow, Syria is scrambling to adjust, and there is some hope of a diplomatic solution.

Let’s not allow the light to go green again.