What to do? No one wants to invade Syria. No one wants to see the United States occupying a second great Arab capital. To be sure, the very knowledge of that reluctance seriously weakens our hand. Nonetheless, we have coercive power short of invasion. We've already employed one, cutting off the pipeline that sends Iraqi oil through Syria. That deprives Assad of about $1 billion out of a government budget of $7.5 billion.

     This should be followed by further ratcheting of economic pressure-- up to and including a blockade of Syrian ports, if we determine that Syria is actively supporting anti-coalition fighters in Iraq.

     We have other instruments beyond economic. We should quietly let Syria know that if its provocations continue--if, for example, it does not turn over the Iraqi leaders it is harboring--we reserve the right of hot pursuit, striking at the time and in the manner of our choosing. This does not mean a land invasion. It could mean a sudden taking out of Damascus' air defenses or destroying one of Assad's Republican Guard equivalents.

     The effect on Assad would be profound: His policy of provocation, designed to show power and command, would instead show weakness and fragility--a potentially fatal demonstration in a regime that, like Saddam's, rests on brute force, a small ethnic/religious minority and a bankrupt Baathist ideology.

     In Iraq, America demonstrated the capacity, extraordinary and historically unique, to destroy a regime while leaving the country intact. Assad needs to learn the lesson of Iraq: Change regime behavior--or suffer regime change.