It's hard to argue with President Barack Obama's call for Bashar al-Assad, the bloodthirsty Syrian dictator, to step down. But it's also hard to discern any logic or consistency in the administration's handling of the ongoing tumult in the Arab world. It is obvious Assad, like Libyan strongman Moammar Gaddafi, has no intention of surrendering. So do we involve ourselves in yet another Middle Eastern war? I don't see how. U.S. military forces are stretched painfully thin. The Pentagon's enormous budget is under new scrutiny, with increasing numbers of Republicans joining Democrats in demanding deep cuts. And polls consistently show the public is weary of war. The call for Assad to go, then, appears more symbolic than substantive. It does put additional pressure on the regime and lays groundwork for further sanctions. But what we need is something the president has refused to provide: an Obama Doctrine governing the use of force to defend civilians against their despotic governments, or at least spelling out the U.S. role in the still-unfolding Arab Spring.