Leading article: Obama's olive branch to Iran

President Barack Obama offered his first overture to the Muslim world when he included his middle name, Hussein, when he swore the oath of office. He offered his second when he specifically mentioned Muslims high up in his inaugural speech. And he made his third when the first foreign leader he phoned after taking office was the Palestinian President, Mahmoud Abbas.

Now, in his most pointed and direct overture so far, Mr Obama has given his first formal television interview as US President to the Dubai-based station, al-Arabiya – not, it should be noted, to al-Jazeera, which has been the station routinely chosen by al-Qa'ida to convey its message of scorn and hostility to the West, but to a station with an equally extensive reach across the region. And he used his broadcast not only to signal a friendlier – or, as he put it, respectful – approach to the Muslim world in general, but to make absolutely clear that he was not excluding Iran. "If," he said, echoing his inauguration speech, "countries like Iran are willing to unclench their fist, they will find an extended hand from us." Thus was George Bush's "axis of evil" summarily excised from US diplomacy and Iran invited to come out of the international cold.

Mr Obama's interview was timed to coincide with the first tour to the region by his Middle East envoy, George Mitchell. The trip does not include Iran but, by mentioning the possibility of improved relations, Mr Obama perhaps hinted that a future trip might. Negotiations about reopening formal relations, broken off after the US embassy siege that followed Iran's Islamic revolution, look increasingly like a priority for the new American administration.

In singling out Iran for special mention, Mr Obama showed canny judgement. If one country holds the key to a host of regional problems – from Hizbollah in Lebanon through Shia militancy in Iraq to nuclear proliferation – it is Iran.

He was issuing not just an invitation, though, but a challenge. With his authority seemingly in decline, President Mahmoud Ahmadinejad may not be in a position to make what would amount to a U-turn in Iranian policy. But the onus is now unequivocally on Tehran to respond.