By Jon Leyne
BBC News, Tehran
Two parallel, and extraordinarily open, battles over policy are being fought out within the administrations in Washington and Tehran. The subject is relations between the United States and Iran.
Iran is considering its response to an EU package of incentives
The choice, at its most stark, is between war and peace. The debate, once again, is over Iran's nuclear programme.
What seems to have provoked the latest heart-searching is a recent Israeli military exercise, clearly intended as a rehearsal for an attack on Iran, therefore also a threat.
At the same time, the details of Iran's response to a package of "incentives" brought to Tehran last month by the European Union envoy Javier Solana are still unknown. The incentives are designed to reopen negotiations over the nuclear issue.
The proverbial "carrot and stick" have never been more openly brandished - though Western diplomats here believe that even to use that crude phrase in private is to insult the intelligence of this proud nation.
The stark alternatives have seen leading figures in both the Iranian and American governments openly defying the accepted wisdom within their administrations.
In Iran, it has been the influential figure of Ali Akbar Velayati, whose comments have provoked great interest.
A former foreign minister, he is now foreign policy adviser to the supreme leader, Ayatollah Khamenei. So he is a key figure, but someone who usually operates behind the scenes.
In a series of newspaper interviews, he handed out barely veiled criticism of President Mahmoud Ahmadinejad's combative rhetoric.
Iranian officials should avoid making "provocative" statements, he said (something Mr Ahmadinejad delights in doing). And he also criticised the strategy of focussing on the non-aligned nations, at the expense of speaking with the great powers (another hallmark of the president's policies).
Most significantly, he urged Iran to accept the European package of incentives, or at least he appeared to.
"Because we know that America and certain other enemies are acting against Iran's national interests and wish Iran not to accept the package, it is expedient to accept it," Ali Akbar Velayati told an Iranian newspaper.
Later, he appeared to clarify his position, when he told Iranian state television: "In my interview, I talked about accepting negotiations, and not accepting the proposed package┐ I said to accept negotiations based on Iran's usual policies."
The distinction might be arcane, as the package of incentives is only intended as a basis for negotiations, not a take-it-or-leave-it offer.
The crucial question is whether Iran is prepared to consider suspending the enrichment of uranium (the process the West fears could be used to make a nuclear bomb).
Mr Ahmadinejad is coming in for criticism for "provocative" statements
Or at least whether Iran might accept a six week freeze on further developments on its programme, in return for a similar freeze on new sanctions - the latest offer put forward by Mr Solana. Ali Akbar Velayati did not make his position clear on either issue.
Accepting either would be a major change of policy. There's little doubt that Mr Ahmadinejad would fight vigorously against any reining back of Iran's nuclear programme, and if he loses this policy battle it would be a major personal blow.
But it's the supreme leader, Ayatollah Khamenei, who has the final say.
In Washington, America's top military officer, the chairman of the Joint Chiefs, Admiral Mike Mullen, was equally outspoken.
He said of an attack on Iran: "This is a very unstable part of the world, and I don't need it to be more unstable."
By contrast, President George W Bush once again refused to rule out the military option, and side-stepped a question about Israel's threatening war games.
Indeed, President Bush's impatience with the diplomatic process was on graphic display during Javier Solana's recent visit to Iran.
Mr Bush rushed to say that Iran had flatly rejected the latest diplomatic proposals, while in actual fact Mr Solana was still in the middle of presenting them, and the Iran government had made (and still has not made) any formal response.
But at the same time in Washington, the State Department is putting forward a proposal to station American diplomats in Tehran for the first time since the seizure of the US embassy in 1979.
Whatever the gloss put on it, it's a move that would be seen as reducing Tehran's diplomatic isolation. Iran's foreign minister has offered a cautious welcome.
While the debate goes on, the clock is ticking. Israel, apparently, is worried about new anti-aircraft defences soon to be supplied to Iran by Russia.
The Israeli government must also be worried that it will never again have such a sympathetic government in Washington.
President Bush himself is counting the days before he leaves office early next year. And in the background, the ever-present question of how far and how fast the Iranian nuclear programme is progressing.
Any Israeli air strike would have to go through American controlled airspace. There would be a severe risk of provoking open war between Iran and the United States - particularly if Iran retaliated against coalition bases in Iraq, or America and its allies in the Gulf.
So no Israeli attack could take place, surely, without at least a degree of American complicity.
Conversely, any meaningful negotiations on the nuclear issue would need a much more active role by Washington, than the present grudging endorsement of EU-led diplomacy.
Any solution to the nuclear issue is inconceivable without tackling the other major differences between Washington and Tehran.
So, two parallel and unresolved debates.
The world may not have noticed much yet. The oil markets certainly have - as prices nudge towards $150 a barrel.