The Obama administration's stated policy is to prevent – not contain – a nuclear-armed Iran, and all indications suggest that that the administration means what it says. Given the destabilizing consequences that would ensure if Tehran acquired nuclear weapons – and the uncertainties, costs and strategic trade-offs associated with containment – this is the right approach. Moreover, having issued a "no-containment" pledge, the United States could not walk back from this policy now without damaging the very credibility it needs to effectively address the Iranian nuclear challenge. The commitment to use all instruments of national power, including the possible use of force, to prevent Iran from acquiring the nuclear weapons should remain firm.
However, this preference for prevention should not be used as an excuse to avoid thinking through the requirements for effective containment. Although the United States is not likely to acquiesce to the emergence of a nuclear-armed Iran, Tehran may be able to achieve an unstoppable breakout capability or develop nuclear weapons in secret before preventive measures have been exhausted. Alternatively, an ineffective military strike could produce minimal damage to Iran's nuclear program while strengthening Tehran's motivation to acquire the bomb. Under any of these scenarios, Washington would likely be forced to shift toward containment regardless of current preferences.
This report, the third in a series on the implications of Iranian nuclearization, outlines a containment strategy to manage and mitigate the dangers associated with a nuclear-armed Iran if prevention efforts – up to and including the use of force – fail.
See full text at the Center for a New American Security: If All Else Fails