Cracks suddenly appear in the ice of the deep-frozen relations between the US and Iran. President Hassan Rouhani emulates Vladimir Putin by writing an opinion piece in the American press oozing goodwill and willingness to co-operate with the US. He gives an interview on American television, repeating: "We have time and again said that in no circumstances would we seek any weapon of mass destruction, including nuclear weapons, nor will we ever."

The air in the Middle East is full of talk of peace and goodwill towards men. Commentators express surprise and even bemusement in the aftermath of the crisis over Syria's chemical weapons. A reason for this is that Washington's focus is now on the removal of the chemical weapons and not the removal of President Bashar al-Assad. It is scarcely feasible to insist that he simultaneously give up his poison gas, engage in peace talks and step down as Syrian leader.

The change in the American focus in Syria is also very important for Iran. So long as Tehran felt that the US, western Europeans, Israel, Saudi Arabia and the Gulf monarchies were aiming at regime change in Damascus as a precursor to regime change in Iran, then it had every reason to throw all its resources into keeping Assad in power, regardless of the political or economic cost. Hezbollah in Lebanon saw itself as facing an existential threat, which is unsurprising given that the anti-Assad forces inside and outside Syria were gleefully admitting that the war was aimed at Iran, Hezbollah and the Shia in general.

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These days the Syrian government speaks of pressing for a ceasefire at any future Geneva peace conference, though their moderation is not quite what it seems. So long as Assad keeps control of the presidency and the security forces, he can offer to share power within the rest of the administration because ministers and ministries have no power. For the opposition, a ceasefire carries the danger that it would freeze the present situation with Assad in control of most of Syria.

How far has the door really opened for negotiations with the US on Iran's nuclear programme and the economic sanctions? There are positive developments if Iran no longer sees confrontation over its nuclear programme as aimed in practice at inflicting a humiliating public defeat on it as a precursor to ending its existence.

The outside world has never quite understood the bizarre but enhanced status of Iran in the Middle East since American military intervention in the region started in 2001. At that time Iran had deeply hostile enemies to the east and the west in the shape of the Taliban in Afghanistan and Saddam Hussein in Iraq. But within a couple of years in the wake of 9/11 the US had got rid of them both. Some clerics in Tehran believed that for Washington to act so much in Iranian interests could only be explained by divine intervention. Of course, Iran had to prevent the US occupation of Iraq becoming a platform for military action against itself, but otherwise it was willing to co-operate covertly with Washington in installing a Shia-Kurdish alliance, replacing the Sunni old regime, as the new rulers in Baghdad. The Iraqi jibe that "the Americans and the Iranians wave their fists at each other over the table but shake hands under it" had a large element of truth in it. One of the reasons why Iraq has not disintegrated since 2011 is that it is much in the interests of Iran and the US to prevent this happening, though at the end of the day their efforts may be insufficient.

But what of Israel? What of Benjamin Netanyahu's blood-curdling threats to launch war against Iranian nuclear facilities if certain red lines were crossed? These Israeli red lines have tended in the past to be rhetorical rather than real. But Netanyahu has been successful in persuading much of the rest of the world to impose damaging economic sanctions on Iranian oil exports and central bank transfers as a preferable option to an Israeli attack.

I have always thought that there is no chance of this. Surely the two biggest, longest-running and most successful bluffs in the world are Israel's threat to attack Iran unilaterally and North Korea's warning that it might invade South Korea, not ruling out the use of nuclear weapons. Israel does not go to war without a green light from the US and even with that green light it has not decisively won a war since 1973.

Netanyahu has successfully manipulated perceptions of the Iranian threat inside and outside Israel to win re-election and fend off international criticism of expanding Israeli settlements on the West Bank, and at the same time has inflicted crippling economic damage on Iran without firing a shot.

But there is another aspect of Iran's status as a threat to Israel, the US and the region that is often forgotten. In the years after the Iranian revolution in 1979 Israel was surprisingly relaxed about developments in Iran, but this changed with the fall of the Soviet Union in 1991. Scott Peterson in his magisterial account of Iran in recent years, Let the Swords Encircle Me, succinctly summarises Israeli concerns: "Anxious that its own strategic utility as a 'bulwark' against Soviet-allied Arab states was losing its shine after the Cold War, Israel launched a campaign in 1992 to convince the US that a new and more dangerous threat had emerged from Iran and the Islamic extremism that the revolution inspired." It is a campaign that has never ended.

But all the time in the background the real war is spreading under its own momentum with largely disregarded bomb attacks by al-Qa'ida killing hundreds every week in Iraq. Ethnic cleansing by Shia and Sunni is eradicating the last mixed areas in and around Baghdad. In Iraq as in Syria the absence of weapons of mass destruction does nothing to prevent killings on a mass scale.