With success, it seems:

VIENNA (Reuters) - U.N. inspectors are set to report that Iran has slowed the expansion of its disputed nuclear program and is cooperating more with them just as major powers prepare to discuss harsh sanctions against Tehran.

Whatever they ultimately decide will hinge on how the report is interpreted: is Iran really shifting policy away from nuclear defiance to open doors to negotiations, or making only temporary gestures timed to keep Russia and China opposed to truly biting sanctions and buy Tehran time to fine-tune uranium enrichment?

Skeptical Western power diplomats leaned toward the second scenario as they awaited the International Atomic Energy Agency (IAEA) report, due for release on Thursday or Friday in Vienna.

"It's hard to see this as anything but a cynical ploy to appear cooperative in the court of public opinion. Sadly, it will probably work," a Western diplomat told Reuters.

The reasons for Iran's slow expansion appear to be technical in nature. And why on earth would Tehran quietly ramp down their program unilaterally when by doing so through negotiations they can extract concessions from the U.S.?

Update: More from Reuters:

Iranian leaders received and rejected in May a proposal from domestic "pragmatists" to halt Iran's nuclear enrichment program to resolve its feud with the West and avoid new U.N. sanctions, Western diplomats said....

They said the proposal, made before Iran's June 12 presidential election but after U.S. President Barack Obama's offer in March of direct talks with Tehran, was ultimately rejected by Supreme Leader Ayatollah Ali Khamenei.

We are headed for a fall-winter showdown.