ACA’s Peter Crail saved me some work with “this post”:http://armscontrolnow.org/2012/04/30/u-s-position-on-iran-enrichment-more-public-recognition-than-policy-shift/#more-2885 illustrating that the P5+1 have, according to their stated policies, been wiling to consider an Iranian enrichment facility for 5+ years now.
As Peter says:
bq. the potential to discuss with Iran the conditions under which it could continue enrichment is not new. In fact, it is built into the proposals that the P5+1 have offered Iran since 2006, spanning the George W. Bush and Barack Obama administrations.