Once again Juan Cole is pointing out important things, http://www.juancole.com. Defense Secretary Robert Gates has given a speech in which he worries that the US will not know what to do if/when Iran achieves the ability to make a nuclear weapon, known as "nuclear latency." While he clearly believes they are pursuing such latency, this is very different from saying that they have an active program of constructing nuclear weapons, which many allege despite longstanding US intel findings that they are not doing so. Cole points out that as long as IAEA inspectors are accessing their sites, this will be extremely unlikely.
OTOH, Iranian Supreme Jurisprudent and Commander-in-Chief, Ali Khamenei, has just made a major speech that Cole provides a translation from in which he reiterates his fatwa against obtaining and particularly using nuclear weapons. He denounces the US for being the only nation in the world to have done so, mentioning Hiroshima. Clearly he is replying to the focus on Iran at the nuclear security summit in Washington organized by Obama, even though Charles Krauthammer has been running around declaring that there was no focus on Iran there.
I support the recently signed treaty with Russia and also most of what went on in Washington, such as securing loose nuclear materials. But the focus on going after the currently-compliant Iran remains a bit mysterious. Actually, it is not so much so. The real object of this exercise is Israel, with its reported 200 or so nuclear bombs, who refused to attend the summit in a fit of pique at Obama's efforts to get it to stop building West Bank settlements and to get back into negotiations with the Palestinians. The Israelis view Iran as an existential threat, clearly viewing Khameini as either lying or powerless. Anyway, it would appear that the US is using up lots of its scarce political capital with China because of this problem of trying to convince the Israelis that "something is being done about about Iran."