Iran's bravado
Iran's current bravado in breaking the IAEA seals on its nuclear plants and stating that it will bar the UN from inspecting its facilities is patently based on the US' current armed forces commitments in the Middle East. The US simply could not handle another conflict in the region, with its forces committed to Iraq and Afghanistan, and Iran's brinkmanship is drawn from Mahmoud Ahmadinejad trying to establish himself as a bold Islamic leader standing up to the Western powers. It's classic Middle Eastern politics, and we can expect to see more shows of defiance by Iran, at least until the US starts withdrawing from Iraq. My take is that they will avoid the negotiating table, probably push the issue to go to the UN Security Council, and then return to the negotiating table to extract maximum concessions, probably some time early next year.