US pressure on Iran's nuclear program is political and long-standing

I just want to put a reference to this here, in addition to the source where I found it, the Iran Affairs blog.

In the year 2000, I was invited to Columbia university by Mr Gary Sick for a review conference on the NPT. I gave a talk about our nuclear activities. A Japanese representative proposed that Iran sign the additional protocol – and this was before the issue of Iran popped up, everything was calm. Before I had the opportunity to answer, an American gentlemen, a retired state department employee who specialised in disarmament, said, and this was exactly the phrase he used: ‘No matter how many times Iran signs the additional protocol, we will keep up our pressure until Iran yields to a political détente. If this is realised, then we will offer them two of our best reactors.’

It comes from a good Financial Times interview with Ali Akbar Salehi, at the time, head of Iran’s Atomic Energy Organisation. The interview is on the Financial Times website and was reposted around the time it was given at the FreeRepublic website, which is a US nearly-fringe right-wing center of discussion.

Iran Affairs, in contact with Gary Sick, confirms that Salehi's recollection is correct. It means that the US uses the nuclear issue as a point of leverage to apply pressure on Iran over wider political issues. In plain words, over Iran's refusal to accept the legitimacy of Israel. There really is no broad political disagreement between Iran and the US that does not resolve to that issue.