By Paul Reynolds
World affairs correspondent BBC New website
Behind Obama's rhetoric are specific demands on specific issues
President Barack Obama's video message to Iran offering a "new beginning" is an imaginative start to his attempt to improve relations - but huge obstacles remain.
In diplomacy such efforts at overcoming major differences sometimes end simply in defining those differences more sharply.
These issues were not directly mentioned by Mr Obama but this is what he is referring to:
• Iran to give up uranium enrichment and accept international offers to provide fuel for nuclear power
- Iran to stop arming Hezbollah in Lebanon and Hamas in Gaza
- Iran to help in achieving peace in Afghanistan and Iraq
- Iran to stop threatening Israel.
Iran will want the following:
- Acceptance of its right to enrich uranium
- An end to UN sanctions
- An end to US sanctions
- An end to America's "colonialist attitudes", including its support for Zionism.
What Obama really means
It is worth deconstructing the president's speech to try to read between the lines.
Flattery is often a good way to start - he talks about the "great" Iranian civilisation and conjures up warm images with references to common family feelings on public holidays.
All this, on the Iranian spring holiday of Nowruz, is an effort to overcome Iranian suspicions that it is held in low esteem by the US.
Perhaps the diplomatically key phrase is this: "My administration is now committed to diplomacy that addresses the full range of issues before us."
He adds: "This process will not be advanced by threats."
This means an end, for the moment at least, to the implied threats of military action.
The president is offering a period of calm in which to allow this diplomacy time to work. He does not however say how long this period will last.
But note how carefully the phrase about threats was written. It does not in fact rule out threats in the future. The absence of threats applies only to the process of diplomacy. If diplomacy fails, threats might return. Mr Obama also means that stopping threats also applies to Iranian threats, especially against Israel.
Incidentally, the US position now diverges quite strongly from the Israeli. The Israelis have recently been making increasingly worried statements about Iran's potential nuclear weapons capacity, suggesting that while diplomacy might come first, military action might come second.
Update: Israeli President Shimon Peres has also broadcast to Iran, on the Farsi service of Israel radio. His tone was much sharper, appealing to the Iranian people but dismissing the leadership as "religious fanatics." He commented: "You can't feed your children enriched uranium." His statement was in effect an appeal for the current Iranian president Mahmoud Ahmadinejad to be voted out in the June election.
The US president also offers carrots, among them "constructive ties between the United States, Iran and the international community" in an "engagement that is honest and grounded in mutual respect".
The ties refer to the potential for diplomatic relations to be restored between the US and Iran, but he does not commit himself openly to that outcome at this stage. "Honest" engagement means that there will be tough talking. "Mutual respect" means that the US will listen.
Close to the bone
Another key phrase: "You, too, have a choice."
This is not a threat but it is a warning. Mr Obama gets close to the bone. Iran, he says, must recognise that rights come with "responsibilities".
This means that Iran might have the right to enrich uranium but should not do so because it is creating concerns about its ambitions. Nor should it stir up trouble in the region, is another subliminal message.
Mr Obama offers another carrot. He accepts that Iran should take its "rightful place in the community of nations", but adds significantly: "That place cannot be reached through terror or arms." The measure of Iran's greatness is not "the capacity to destroy".
"Terror or arms" means Hezbollah and Hamas and maybe its own military build-up.
The "capacity to destroy" is a reference to nuclear weapons, even though Iran says that it will not build them, and to Iranian missile development.
Importantly, the president implicitly offers an end to sanctions by saying that he wants a future with "greater opportunities for partnership and commerce". At this stage he is offering only "greater" opportunities, not the full opening, but the deal is in prospect.
He also looks to a future "where you and all your neighbours and the wider world can live in greater security...". "All" the neighbours include Israel, of course.
There is a very ambitious agenda here. The process suggests direct talks if that is what Iran wants.
Update: The response from Iran has been hostile so far. Its Supreme Leader Ayatollah Khamenei said that President Obama's "unconditional commitment to defend Israel's security" meant that he was following "the same wrong path as the Bush administration."
And President Ahmadinejad said: "Change means giving up your satanic, coercive and aggressive ways."