President Barack Obama yesterday declared that the United States will “do what we must” to prevent Iran acquiring a nuclear weapon as UN Secretary-General Ban Ki-moon warned against threatening attacks whose consequences would be devastating.

Taking the podium at the United Nations six weeks before the US presidential election, Obama sought to counter criticism of his foreign record by Republican rival Mitt Romney, who has accused him of mishandling the Arab Spring uprisings, damaging ties with Israel and not being tough enough on Iran.

Obama also challenged world leaders to stand united against anti-American violence that has swept many Muslim countries in recent weeks and to promote tolerance amid anger over a crudely made video that offended Islam. “There are no words that excuse the killing of innocents,” he said.

Seeking to step up pressure on Iran, Obama told the UN General Assembly there is still time for a diplomacy but that “time is not unlimited”.

His tough talk appeared aimed at easing Israeli concerns about US resolve to curb Tehran’s nuclear drive, as he reasserted before the world body that he would never let Iran develop an atomic bomb and then simply contain the problem.

But he stopped short of meeting Israeli Prime Minister Benjamin Netanyahu’s demand to set a specific “red line” that Iran must not cross if it is to avoid military action, and did not go much farther in his rhetoric than previously.

“A nuclear-armed Iran is not a challenge that can be contained,” he said.

“It would threaten the elimination of Israel, the security of Gulf nations and the stability of the global economy.

“The United States will do what we must to prevent Iran from obtaining a nuclear weapon.”

In an apparent allusion to recent comments by US, Israeli and Iranian officials, Ban opened the annual UN General Assembly by warning states against threatening to attack one another and sounded a pessimistic note about Arab-Israeli peace.

“I also reject both the language of delegitimisation and threats of potential military action by one state against another,” Ban said. “Any such attacks would be devastating.”

US officials have repeatedly said that all options are on the table against Iran – code for a possible military strike – while Israel’s Netanyahu has called for a US ultimatum to Iran. But Obama did not repeat that line in his speech.

On Monday, Iranian President Mahmoud Ahmadinejad said Israel has no roots in the Middle East and would be “eliminated”. The White House dismissed his comments as “disgusting”.

Without naming Ahmadinejad, Obama took a veiled swipe at him yesterday, saying the world must “leave behind” those who deny the Holocaust or reject Israel’s right to exist.

Obama also sought to reassure US voters that he is doing everything he can to head off any more violence like the September 11 attack in Libya, which killed the U.S. ambassador and three of his colleagues.

A wave of Muslim rage over an anti-Islam video made in California has swept the Middle East, North Africa and South Asia. Americans were stunned by images of US flags again burning in the Muslim world, the focus of intense personal diplomacy by the president at the start of his term.

“The attacks of the last two weeks are not simply an assault on America. They are also an assault on the very ideals upon which the United Nations was founded,” Obama told the assembled world leaders.

This eruption of violence has confronted Obama with the worst setback yet in his efforts to keep the Arab Spring revolutions from turning against the US – and has demonstrated that he has few easy options.

He also had harsh words for Syrian President Bashar al-Assad, saying his regime “must come to an end”, a reminder of Assad’s defiance of international calls for him to end a bloody 18-month crackdown and step aside.

And Obama renewed his call for Israeli-Palestinian peace talks – something he promised to make a priority when he took office but has failed to advance.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.