By Frances Harrison
BBC News, Tehran
The details of exactly what nuclear research Iran plans to conduct at its uranium enrichment site in Natanz are not yet clear.
The majority of Iranians support the resumption of nuclear research
Iran has said nuclear fuel production remains suspended but it looks as if it is now going to research how to make that fuel.
That is not reassuring for the West, which fears that same technology can be used for making weapons.
But the first reaction in Iran was from a group of parliamentarians who drew up a letter welcoming the decision to resume research.
For the majority nuclear power is a nationalistic issue and there is deep resentment that the west wants to prevent Iran from making technological progress
Open criticism is unlikely because on the eve of the United Nations seals being broken the country's supreme leader, Ayatollah Ali Khamenei, indicated his support for the step.
He stressed that peaceful nuclear technology was Iran's inalienable right.
And he indicated Iran was preparing itself psychologically for the prospect of punitive action, saying sanctions had just made Iran more self reliant in the past and would have no effect in the future.
Reformists, who are now in opposition, have remained relatively silent on the nuclear issue.
The approach of Iran's former chief nuclear negotiator, Hassan Rowhani, was to keep the negotiating process going and hope to avoid referral to the UN Security Council while not making long term concessions.
Iran's president has taken a tougher stance than reformists
Some analysts have suggested the reformists were willing to bargain away the country's nuclear programme if the price was right.
But without the involvement of the Americans in the negotiating process there was doubt about whether the incentives would ever have been attractive enough for Iran.
While there are few dissenting voices in public, reformists will be alarmed by the increasing talk of referral to the Security Council.
And they will be worried that Russia may side with other permanent Security Council members if it came to a vote against Iran.
If Russia deserted Iran this would put pressure on China to follow suit.
But the new government of President Mahmoud Ahmadinejad has taken a much tougher line than the reformists before them on a range of foreign policy issues, including the nuclear one.
The radical new president seems to want to go back to the early days of the 1979 Islamic Revolution and he hopes to use the nuclear issue to rally Iranians and the wider Muslim world behind him.
A few Iranians outside the establishment might think the political costs of pursuing nuclear technology are not worth it.
But for the majority nuclear power is a nationalistic issue and there is deep resentment that the west wants to prevent Iran from making technological progress.