奥巴马呼吁建立独立的巴勒斯坦国

A hurried arrival at the United Nations, President Obama was late for his speech to world leaders. At the podium, his overriding concern: the current fragile Israeli-Palestinian peace negotiations and a brave diplomatic prediction.

"This time we should reach for what's best within ourselves. If we do, when we come back here next year, we can have an agreement that will lead to a new member of the United Nations-- an independent, sovereign state of Palestine living in peace with Israel."

A ripple of applause. But there's a specter of wider Middle East turbulence that American fears - the danger of Iran acquiring nuclear weapons. So Mr. Obama also had a message for the Iranian leadership.

"The door remians open to diplomacy should Iran choose to walk through it. But the Iranian government must demonstrate a clear, credible commitment and confirm to the world the peaceful intent of its nuclear program."

Not the President Ahmadinejad was in the hall to hear that. Grinning broadly, he pointedly walked into the building some 30 minutes later, a leader with a dubious honour of being enemy No.1 at the minute, the target of bus shelter posters and angry street protests. What worries western politicians is that he'll resist both offers of talks and pressure from tightening sanctions, pushing everyone towards a dangerous new confrontation.

"I think the single biggest risk is that Iran miscalculates. President Obama, he's made every effort to find a way through. You know, so, I think they should pay attention to that and realize he has done that, in a sense, in order to say to them I've tried my hardest with you."

Here at the United Nations, there's definitely a renewed effort to get diplomacy with Iran going, and a huge determination by President Obama to get a breakthrough on Mideast peace negotiations. Bold ambitions, high sets, making a reality will be much more difficult.

Bridget Kendall, BBC News, at the United Nations.