The reports that banned weapons of mass destruction were used in the 2 1/2-year-old Syrian civil war have spurred international outrage and calls for punitive airstrikes to degrade Dr Assad's military capability. In a clear signal of change under his month-old administration, Mr Rouhani said on Thursday that his government had assumed responsibility for nuclear talks with the International Atomic Energy Agency in Vienna, which are set to resume September 27 after a five-month hiatus. The negotiations, stalemated for years by Iranian foreign policy hard-liners loyal to supreme leader Ayatollah Ali Khamenei, were previously under the control of the religious hierarchy's Supreme National Security Council. Numerous meetings between IAEA officials and Iran's former chief nuclear negotiator, Khamenei adviser Saeed Jalili, failed to yield progress during the Ahmadinejad regime. Nor did 10 sessions over the last 17 months between Jalili and six major world powers, including the US, move Tehran any closer to agreeing to stop enriching uranium to levels suitable for weapons production. Renouncing high-level enrichment and any nuclear military ambitions are key conditions set down by the six nations — which also include Russia, China, Britain, France and Germany — for easing sanctions that have crippled Iran's economy. Analysts hailed the shift on nuclear talks as an opportunity for Mr Rouhani to make good on his campaign pledge to improve relations with the West.

"A U-turn in Iranian diplomacy occurred today," said Saeed Laylaz, an economist and political analyst. "This is very important, as we understand it to mean that the supreme leader (Khamenei) is allowing the Foreign Ministry to handle the nuclear talks. ... We can see a new chapter has already opened vis-a-vis relations with the West." Mr Laylaz also pointed to Mr Rouhani's modest pledge on Wednesday to support Syria with humanitarian aid if Dr Assad's forces come under attack for the alleged use of poison gas. If Syria is targeted with Western airstrikes, "the Islamic Republic of Iran will do its religious and humanitarian duty and send food and medicine," Mr Rouhani told the Assembly of Experts, a panel of Islamic theologians that chooses and advises the supreme leader. "Iran will not do anything to openly announce assistance to the Syrian regime if Syria is attacked by the United States," said Nader Karimi Joni, an independent analyst and chief editor of the sociopolitical magazine Gozaresh. He and Mr Laylaz interpreted Mr Rouhani's reserved support for Syria as following through on a campaign promise to give priority to Iranians' desire for an end to their international isolation. The nuclear policy takeover "reinforces the message of Rouhani during the election that Iran is looking to turn around its relations with the world and that he appreciates that the only viable mechanism for doing that is re-engaging in the nuclear talks in a very different way than it has in the past eight years," said Suzanne Maloney, a senior fellow at the Brookings Institution's Saban Center for Middle East Policy.

"Moving the portfolio from the Supreme National Security Council to the Foreign Ministry certainly underscores Rouhani's personal identification with the progress of the talks,"Ms Maloney said. "Most importantly, this puts at the helm of the talks the Iranian who is best positioned to engage in serious and productive dialogue with Washington," Maloney said of Foreign Minister Mohammad Javad Zarif, a former Iranian ambassador to the United Nations who has spent much of his adult life in the United States. Still, it remains unclear whether Rouhani and the moderates will prevail in keeping their distance from Assad. But Iranian leaders have been hedging their support for the Syrian government since the start of the civil war there, Maloney said, "and it is quite clear that there is no consensus in the Iranian leadership that Iran should be defending Assad." Los Angeles Times