In light of Secretary Clinton's determined effort to forestall a Iran nuclear deal brokered by Turkey (see below), I think it's pretty clear that Iran is desperate for a deal and the United States is equally desperate to block one.
I think the only thing that could have persuaded Turkey's Prime Minister Erdogan to turn away from negotiations (negotiations that, in my opinion, would have a very good chance of yielding an agreement) was an assurance by the United States that the NPT Review Conference would see a dramatic announcement by Israel that it's ready to engage with the Obama non-proliferation regime: maybe not joining the NPT outright, but maybe signing the CTBT and/or going along with the fissile material freeze initiative.
This kind of concession, even if symbolic, would probably be enough to spike the guns of Egypt and the Non-Aligned Movement at the NPT Revcon and justify Turkey's move to the sidelines.
Israel's price for this concession would be continuation of the Iran confrontation through sanctions until Iran is denuclearized and "trust" is restored i.e. never.
In the meantime, the stress of stepped up sanctions would keep Iran in a state of internal political disarray that Israel would find quite gratifying.
This would, I believe, represent a 180 from what the Obama administration hoped to accomplish in 2009: a rapprochement with Iran that would compel Israel's entry into the non-proliferation regime.
Instead, the U.S. has retreated from a win-win to a zero-sum arrangement.
Washington doesn't get reduced tensions in the Middle East and a more productive relationship with Iran; it gets a perpetuation of the current debilitating arrangement with Israel enjoying U.S. patronage and Iran back in the doghouse.
Let's see what happens.