With the Iraq war behind us and our departure from Afghanistan underway, the United States could be entering a well-earned respite from fighting. But even before peace can take hold, hawks are singing the old country song: "I've enjoyed as much of this as I can stand."

They see a way to escape in Syria, where rebels have been fighting the government of Bashar al-Assad for more than two years. For most of that time, Republican Sens. John McCain of Arizona and Lindsey Graham of South Carolina have been leading the call for U.S. military intervention—and President Barack Obama has been declining the invitation.

His critics, however, think they now have him where they want him. Obama earlier said that any use of chemical weapons by Assad would be a "game changer," and last week, the White House said it thinks he's used sarin gas, though it said further investigation would be needed.

Obama was careful in his Tuesday news conference to emphasize the uncertainties: "What we now have is evidence that chemical weapons have been used inside of Syria, but we don't know how they were used, when they were used, who used them."

So far he's settled for a minimalist response: possibly sending weapons to the insurgents. He added that as a result of the gas attacks, "there are some options that we might not otherwise exercise that we would strongly consider."

Strongly consider? My advice is to consider them till the cows come home—just don't actually adopt them. The options at hand are generally dangerous, ineffectual or both.

Graham says the United States has to act because "the greatest risk is a failed state with chemical weapons falling in the hands of radical Islamists." In reality, the greatest risk is putting our troops into a civil war where they could end up targeted by both sides, as we ingeniously arranged in Iraq. As we showed there, removing a dictator can unleash endless sectarian conflict. Fortunately, even McCain says he doesn't favor American boots on the ground.

The preferred instrument of hawks is air power—to enforce a no-fly zone against the regime or destroy military assets. But it's a lot easier said than done.

To begin with, Syria has one of the best air defense systems in the world, built with help from Russia. "Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, frequently singles out Mr. Assad's air-defense prowess as the biggest single obstacle to U.S. intervention," reports The Wall Street Journal. Casualty-free intervention, a la Libya, is not a realistic possibility in Syria.

Taking out Assad's anti-aircraft batteries—or tanks, trucks and infantry—would inflict heavy casualties on the people we'd like to help. Much of the fighting takes place in cities, where civilians are dangerously exposed.

Even precision bombs launched from drones, notes University of Chicago scholar Robert Pape, author of "Bombing to Win," have a blast radius of up to 50 feet, and their shock waves can easily bring down neighboring buildings. Our drone strikes in rural Pakistan do enough collateral damage to sow deep anger among the locals. In urban Syria, civilian fatalities would be far higher.

U.S. bombing might backfire by inducing the regime to make full use of its chemical weapons while it can. Air power also can't head off the danger of those supplies falling into the hands of Islamic radicals. Bombing chemical weapons sites, even if we could identify them, would mean spewing deadly nerve agents over a wide area—which sort of resembles the outcome we're trying to prevent.

But securing them from militants would require ground forces—as many as 75,000, according to the Pentagon. Transporting the stockpiles out of the country or destroying them would take a lot of troops and time. "There is no exit strategy with this option either," says Michael Desch, a national security scholar at the University of Notre Dame.

Graham doesn't mention that those dangerous Islamic radicals are among the people we'd be helping. As The New York Times recently reported, "Nowhere in rebel-controlled Syria is there a secular fighting force to speak of." No one relishes the thought of terrorist groups getting poison gas. But that doesn't mean anyone has a good way to prevent it.

Advocates of intervention think we couldn't make the problems of Syria worse. But we could make them worse. Scarier still, we could make them ours.