Stephen Peter Rosen, of Middle East Strategy at Harvard, draws rather different conclusions from the NIE Report from those its authors probably intended.
In my view, the Iran program halted in 2003 because of the massive and initially successful American use of military power in Iraq. The United States offered no â€œcarrotsâ€ to Iran, but only wielded an enormous stick. This increased the Iraniansâ€™ desire to minimize the risks to themselves, and so they halted programs that could unambiguously be identified as a nuclear weapons program. They were guarding themselves against the exposure of a weapons program by US or Israeli clandestine intelligence collection, and were not trying to signal the United States that they were looking to negotiate. They did not publicly announce this halt because if they did so, they would be perceived as weak within Iran, and within the region. By continuing the enrichment program, they kept the weapon option open.
If this is true, the Iranian government responds to imminent threats of force, not economic sanctions or diplomatic concessions. If that is the case, as the threat of US use of force goes down, the likelihood that Iran restarts its program goes up. Since the threat of US use of force went down in 2007, it is likely that the program restarted in that time frame. The threat of Israeli use of force, however, remained high, and went up after the attack on Syria. The NIE, however, ensured that there would be no US or Israeli use of force for the foreseeable future. So the prediction is that warhead production activity has restarted, and will produce a useable gun-type design quickly. Given observable uranium enrichment activity, enough uranium will be available for one bomb in one year. It does not makes sense for a country to test its first and only weapon when it has none in reserve to deter attacks. So the first test is not likely before two years from now or late 2009.
What will Iranian behavior be after the first test? All countries, with the exception of India, that have developed their own nuclear weapon, have transferred that technology to other countries.