the USS John C. Stennis aircraft carrier, which left at the end of December during Iranian naval manoeuvres, should not return - an order interpreted by some observers in Iran and Washington as a blanket threat to any U.S. carriers.

Only a few weeks ago Tehran was threatening to close the Strait of Hormuz, used by a third of the world's seaborne oil trade, if new sanctions cripple its oil exports - exactly the effect Washington and Europe are aiming for.

European Union foreign ministers are set to meet on Monday to agree a ban on importing oil from Iran and sanctions signed by U.S. President Barack Obama on New Year's Eve aim to make it impossible for countries around the world to buy Iranian crude.

Iran's First Vice President Mohammadmid-2010.

"They were saying then: 'Let's have talks,' but it wasn't followed up by any kind of concrete commitment," he said, adding that, despite several public declarations of goodwill, Tehran has yet to deliver a reply to a letter Ashton sent to Tehran on October 21 letter offering to resume talks.

"Iran is not softening its stance," said Meir Javedanfar, Iran analyst and co-author of "The Nuclear Sphinx of Tehran".

"It's changing its strategy after realising that its ill-timed and exaggerated threat to close the Strait of Hormuz in case of sanctions caused more damage to its stance and position than anyone else."

The change in Iran's rhetoric could add to the bearish direction of oil prices which were down on Friday due to signs of reduced demand.

"The result of Iran softening