Michael Makovsky and Blaise Misztal write in the Washington Post that President Obama is now trying only to contain Iran:
As recent events underscore the growing Iranian nuclear threat, the Obama administration appears to be pivoting toward a policy of containment. The emphasis of its rhetoric has shifted from preventing an “unacceptable” nuclear Iran to “isolating” it. When coupled with recent weaker action against Iran, we fear it signals a tacit policy change.
The authors go on to argue that the Obama administration should be using "all elements of American power" to deal with Iran, since containment won't work:
The administration’s alternative to prevention — isolation — implies containment. But a nuclear Iran could not be contained as the Soviet Union was. Containment requires credibility, a resource United States will have drained if, after numerous warnings to the contrary, we permit Tehran to cross the nuclear threshold. And no matter how isolated, a nuclear Iran is likely to spark a destabilizing cascade of proliferation. Despite its own isolation, North Korea shares its nuclear technology. Iran might, too. Tehran’s enemies, led by Saudi Arabia, would seek safety behind their own nuclear deterrent. And Iran and Israel, as former defense undersecretary Eric Edelman has argued, would have incentives to initiate a nuclear first strike, potentially dragging the United States into the conflict. All this would severely diminish U.S. influence and drive up oil prices.
Tom Donnelly, likewise, identifies Obama's containment policy, but says it's "a very mild form of containment, one that imposes few costs on the Islamic Republic." Donnelly concludes:
In the after-midnight hour when the Obama retreat is complete, the United States would find itself with few options at the chiming of the nuclear clock. Containing and deterring a nuclear Iran would be a long, costly, and risky endeavor, and a task made immensely more difficult by the withdrawals from Iraq and Afghanistan and by the large cuts that will cripple the U.S. military. Time is short—but there is still time, and not simply to prepare for the extraordinary danger of a nuclear Iran, but to avert it.
Whole thing here.