By Roger Hardy
Middle East analyst, BBC News
With Condoleezza Rice at the State Department, pragmatism has made a comeback
In a significant shift of policy, the United States is offering to join Europe in talks with Iran on its nuclear programme, if Tehran suspends enrichment of uranium.
One way to understand the shift is to compare its handling of Iran in President Bush's second term with its approach to Iraq in his first.
Then it alienated allies and its resort to the United Nations was half-hearted.
There was a widespread feeling Washington was bent on war, regardless of the extent of international opposition.
Now the Americans are bogged down in Iraq and most experts think that, far from helping defeat al-Qaeda and Islamic extremism, the war has served to fuel the "global jihad".
This has led to a change of approach.
In President Bush's second term, with Condoleezza Rice at the helm in the State Department, pragmatism has made a comeback.
If the first term was dominated by "hard power", now "soft power" is back in fashion.
In other words, force is a blunt instrument for effecting change - especially if it leaves you acting virtually alone.
"Soft power" - non-military means such as diplomacy and economic leverage and working with allies - is less exciting but also less risky.
On Iran, Dr Rice's first big shift was to allow Britain, France and Germany (the EU3) to make the running in talks designed to persuade Iran to give up uranium enrichment.
Iran played along. But from its point of view, while the Europeans could talk, only Washington could deliver.
So now, in a second shift, Dr Rice has said America would join multilateral talks - but on strict conditions.
Will it work?
The aim is to isolate Iran and deprive it of any excuse for further obstinacy or prevarication.
If the Americans can create a strong international consensus - bringing Russia and China on board in an unambiguous way - that would be a significant achievement.
It is possible the hardliners in the Iranian leadership may press on regardless.
Having invested so much political capital in becoming a nuclear power, they may refuse to back down.
Hardliners may welcome confrontation as a way of breathing new fire into the revolution
They may believe America is bogged down in Iraq and so in no position to attempt "regime change" in Tehran.
Some hardliners may even welcome confrontation as a way of breathing new fire into the Islamic revolution.
The pragmatists in Tehran, on the other hand, may argue that complete international isolation - and the imposition of economic sanctions - should be avoided.
Taking on America is one thing; taking on the world another.