UPDATE: Anthony Cordesman has a valuable update on the CSIS site, in which he discusses the pluses and minuses of the administration playing good cop and Congress playing bad cop toward Iran. Really worth reading, but a few highlights. First, on U.S. aims:
The United States now has every incentive to leverage the success of existing sanctions, take full advantage of the current climate, and to try to make the current negotiations work. They are by far the safest way to remove an Iranian nuclear threat, and it is critical to remember what the threat really is: The real objective is to deny Iran military capability, not to try to deny it technology it has already acquired.
On the strength of the emerging potential deal:
The P5+1 and the United States have not yet made fully public all of the terms of the progress they made in defining and implementing the terms of the interim agreement ...
At least to date, however, the limits on Iran in terms of permitted activities, improved transparency, and increased inspection would make even the most covert production, testing, and deployment of nuclear weapons extraordinarily difficult. Iran might quietly get to the point of a crude test of a gun or implosion device, but this test could scarcely then remain covert...
It is extraordinarily difficult to believe Iran could actually deploy reliable nuclear missile warheads and bombs without being detected
On the Congress's role as hard-line bad cop:
The key to success, however, will be for the “bad cop” to avoid pushing to the point of failure. The best way to move forward is to do what the Senate Majority Leader, Senator Harry Reid, evidently has already proposed to do: keep the option of new sanctions legislation constantly open, but not confront Iran and other nations by passing such legislation if and when the negotiations fail, or Iran is shown to violate an agreement.
Defer a vote on new sanctions until the ongoing efforts to fully define and create enforcement provisions for interim agreement effort fail or Iran violates them. And if Iran does move forward and complies with the interim agreement – defer a sanctions vote until it is clear whether Iran agrees to and complies with a permanent agreement.
Overall: This bill is a reckless and destructive gesture, and Democrats from Cory Booker to Mark Warner to Michael Bennet to Richard Blumenthal should give it a careful look and back off.