Iran threatens to expand its nuclear program, with yet another reasonable justification, if we could believe them. We’ve found some significant discrepancies, but we haven’t really found a smoking gun that would warrant military action. Economic sanctions are pretty ineffectual; so, it doesn’t really matter whether we get some imposed despite China’s resistance, or not.
Nobody is talking about the real problem, which is that Israel has many atomic bombs, and we have basically turned a blind eye to bombs developed by India and Pakistan. Arguably, the Pakistani bomb offsets the Israeli bomb, but Pakistan is fast becoming a failed state; so who know what will happen to the Pakistani bombs. They could fall to al–Qaeda, or the US military could take them over to prevent al–Qaeda from getting them. So, Iran is working working on a Muslim bomb that it can count on to counter to the Jewish bombs.
Unless the US does something about Israel, it’s unlikely that it can do anything about the Iranian bomb. It’s not clear that the Iranians really want to build a bomb; they may just want to be able to build a bomb if they feel the need for one. But they are a lot more likely to feel the need for one as long as Israel has many.