Iran fails to answer questions on nuclear research, says IAEA Iranian officials agreed to meet the inspectors again to discuss handing over the information - but not until after Nov 24. This means that the negotiations will start in Vienna with these two issues remaining unresolved in breach of the agreement reached in May. "The Iranians are holding these transparency measures hostage to the negotiations with the world powers," said Mark Fitzpatrick, a non-proliferation expert at the International Institute for Strategic Studies. It's not surprising because answering these questions truthfully would land them in hot water - they would probably have to admit to doing some things that were not kosher. However, Mr Fitzpatrick said that Iran's failure to address these questions would make little difference to the chances of achieving a final agreement in Vienna. Mr Obama has made settling the nuclear confrontation a central goal of his presidency. As well as allowing Mr Kerry to negotiate directly with Iran, the president has tried to open a channel to his counterpart in Tehran. Starting in 2009, Mr Obama is understood to have written at least four letters to Ayatollah Khamenei. The latest, sent last month, was reported to offer America's cooperation with Iran in the struggle against the Islamic State of Iraq and the Levant (Isil) - but only if the nuclear question was settled. By raising the prospect of US-Iran cooperation, Mr Obama was trying to reassure Ayatollah Khamenei that "regime change" was not America's goal. Sir Richard Dalton, a former British ambassador to Iran, said the president's efforts were "absolutely right," adding that the letter appeared designed to "dent the impression that the US is irredeemably hostile and bent on regime change." But Mr Obama's bid to ease tensions with Iran has been criticised at home. Emboldened by their capture of the Senate this week, the Republicans denounced the president's suggestion that America could work with Iran. Senator John McCain, who is set to become the next chairman of the armed services committee, said it was "immoral and shameful that somehow we are playing footsie with the Iranians." He accused the administration of directing America's military offensive in Syria away from forces loyal to President Bashar al-Assad to avoid offending Iran. At a press conference this week, Mr Obama sounded optimistic about the chances of reaching agreement with Iran by November 24, describing the negotiations so far as "constructive." However, he warned that success would hinge on whether Ayatollah Khamenei and other Iranian leaders could bring themselves to sign a deal with a country they denounce as the "Great Satan." The president said: "There's a sizeable portion of the [Iranian] political elite that, you know, cut its teeth on anti-Americanism. Whether they can manage to say 'yes' to what clearly would be better for Iran, better for the region and better for the world is an open question. Mr Obama would also have to sell any agreement in America, a task made harder now that Republicans control the Senate. Any comprehensive deal would require the US to lift sanctions on Iran.