By Jon Leyne
BBC News, Tehran
It is always difficult to spot the difference between bluster and genuine defiance.
Iranian leaders believe the warnings are psychological warfare
But Iran's response to the recent threats of war seems to mix real defiance with a degree, almost, of complacency.
There is a firm belief here in Tehran that the United States is simply not in a position to attack Iran.
"I don't think anyone in Iran has taken these threats seriously. They think that it's more rhetoric and for putting extra psychological pressure on Iran," says Sadegh Zibakalam of Tehran University.
As the newspaper Jomhuri-ye Islami put it on Monday morning: "Iranians are deeply aware of the fact that America is so busy in Iraq and Afghanistan that it cannot do anything against Iran."
Whether most Iranians truly believe that, it is impossible to tell.
But it is certainly the accepted wisdom among those close to President Mahmoud Ahmadinejad and the supreme leader, Ayatollah Ali Khamenei.
It is repeated so often in the media - at least the media close to the leadership - it has become a cliche difficult to debate or question.
In fact President Ahmadinejad is increasingly confident there will not even be fresh UN sanctions over Iran's controversial nuclear programme.
As he has put it several times recently: "The nuclear issue as a political issue is closed... the Iranian file is finished with."
The Iranian leadership believes the current warnings, from both Washington and Paris, are just psychological warfare. So the response has been to increase the volume in return.
At Friday prayers last week, Ayatollah Khamenei was particularly blunt.
Mr Ahmadinejad is to visit the UN General Assembly this month
He accused US President George W Bush of being a war criminal, and said the US plans for the Middle East had been comprehensively defeated.
"As far as the president is concerned, as far as the supreme leader is concerned, the United States is simply trying to wage a psychological war against Iran and we must be strong enough, we must be resolute enough," said Dr Zibakalam.
"We must not show them that we have been frightened and we are going to back down."
Ayatollah Khamenei has told those around him that there are only two countries truly opposed to the Iranian nuclear programme: the United States and Great Britain. (Iran does not recognise the existence of Israel as a country.)
There even seems to be a belief that Washington can somehow be overwhelmed by international opinion.
So President Ahmadinejad is on a public relations campaign to convince the world of Iran's peaceful intentions - culminating in a visit to the UN General Assembly in New York this month.
How wars start
An anti-war protest in Washington at the weekend was given major coverage in the Iranian press - all evidence for Tehran that US public opinion simply will not allow an attack on Iran.
It is certainly true that Washington faces a struggle to win approval for new UN sanctions against Iran.
By agreeing to talks with the International Atomic Energy Agency, Iran has won the grudging support of Russia and China, at least for the moment.
Tehran says President Vladimir Putin of Russia is even going to visit Iran next month.
So the next two or three months could well be a time of plenty of talk, and little movement over Iran's nuclear programme.
But all the while, Washington's list of grievances against Tehran grows. Iran is blamed (or made a scapegoat) for violence in Iraq and Afghanistan.
The idea that, given enough time, Washington will somehow forget about Iran is wishful thinking in the extreme.
The worrying thing is not just that Washington and Tehran disagree. More fundamentally, they completely misunderstand each others' intentions. And that is how wars start.