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.