Reuel Marc Gerecht writes in the Wall Street Journal:
Khamenei probably approved a strike in Washington because he no longer fears American military might. Iran's advancing nuclear-weapons program has undoubtedly fortified his spine, as American presidents have called it "unacceptable" yet done nothing about it. And neither George W. Bush nor Barack Obama retaliated against Iran's murderous missions in Iraq and Afghanistan.
President Obama has clearly shown he wants no part—or any Israeli part—in a preventive military strike against Iran's nuclear sites. And Mr. Obama has pulled almost all U.S. troops out of Iraq and clearly wants to do the same in Afghanistan. Many Americans may view that as a blessing, but it is also clearly a sign that Washington no longer has the desire to maintain hegemony in the Middle East.
That's an invitation to someone like Khamenei to push further, to attack both America and Iran's most detested Middle Eastern rival, the virulently anti-Shiite Saudi Arabia. In the Islamic Republic's conspiracy-laden world, the Saudis are part of the anti-Iranian American Arab realm, which is currently trying to down Iran's close ally, Bashar al-Assad's Syria, and squash the Shiites of Bahrain. Blowing up the Saudi ambassador in Washington would be an appealing counterstroke against the two foreign forces that Khamenei detests most.
The Obama administration will be tempted to respond against Iran with further unilateral and multilateral sanctions. More sanctions aren't a bad idea—targeted sanctions against the Revolutionary Guards and the sale of gasoline made from Iranian crude can hurt Tehran financially. But they will not scare it. The White House needs to respond militarily to this outrage. If we don't, we are asking for it.
Whole thing here.