Megan K. Stack: I fail to see how creating a political vacuum that could evolve in countless, unpredictable ways is expected to make anyone safer. There’s some vague idea that the Iranian people are all opposed to their government and will come together to create a new government. I don’t think history supports that expectation. Our leaders don’t seem to have learned anything from U.S. interventions in Iraq, Afghanistan and Libya. Sure, the U.S. military can kill all the leadership. And then what?