President Bashar al-Assad is once more one of the "triple pillars" of the Middle East. We may not like that. George Bush may curse the day his invasion of Iraq helped to shore up the power of the Caliph of Damascus.

But Mr Assad's latest trip to Tehran – just three weeks after he helped to toast the overthrow of the King of France beside President Nicolas Sarkozy – seals his place in history. Without a shot being fired, Mr Assad has ensured anyone who wants anything in the Middle East has got to talk to Syria. He's done nothing – and he's won.

The Europeans like to think – or, at least, M. Sarkozy likes to think – Mr Assad was in Tehran to persuade President Ahmadinejad not to go nuclear. Even Sana, the official Syrian news agency, was almost frank about it. The purpose of the Assad visit was "to consult on the nuclear issue and the right of states to peaceful enrichment" and "exchange ideas aimed at clarifying Iran's commitment to all international agreements". Mr Assad was M. Sarkozy's point-man.

The inevitable followed. President Ahmadinejad expressed his belief that only diplomacy could deliver us from the nuclear tangle, leaving us with Mr Assad's statement to M. Sarkozy on 12 July. Asked if the Iranians were trying to develop a nuclear bomb, Mr Assad told the French President he had asked the Iranians this very question, they had replied in the negative and this was good enough for him.

What's interesting about this is that Mr Assad probably believes it. Indeed, it may be true. Of all people, he knows about trust – or the lack of it – and his father's main foreign policy achievement was probably maintaining Syria's relations with Iran. In the face of every appeal to abandon Tehran, he refused. The younger Assad's talks with Israel via Turkey suggested to the Washington commentariat that he may at last be abandoning Iran and the return of Golan was more powerful to Bashar al-Assad than Syria's all-embracing role as the postman of Tehran. Not so.

For there was Mr Assad in Tehran this weekend, praising the mutual relationship between Iran and Syria and talking with Mr Ahmadinejad about the Israeli-US "conspiracy". The Syrian-supported Hizbollah's retrieval of living prisoners from Israel in return for the remains of two dead Israeli soldiers, was described by Mr Assad as "one of the achievements of the resistance". Which, in a way, it was. For Hizbollah's allies in the Lebanese government now have veto power over the cabinet majority, and Syria's power has returned to Beirut without the cost of sending a single Syrian soldier.

In other words, Syria kept its cool. When the US invaded Iraq, the world wondered if its tanks would turn left to Damascus or right to Tehran. In fact, they lie still in the Iraqi desert, where US generals still variously accuse Iran and Syria of encouraging the insurgency against them. If Washington wants to leave Iraq, it can call Damascus for help.

And the real cost? The US will have to restore full relations with Syria. It will have to continue talks with Iran. It will have to thank Iran for its "help" in Iraq – most of the Iraqi government, after all, was nurtured in the Islamic Republic during the Iran-Iraq war in which the US took Saddam's side. It will have to accept Iran is not making a nuclear bomb. And it will have to prevent Israel staging a bombing spectacular on Iran which will destroy every hope of US mediation. It will also have to produce a just Middle East peace. McCain or Obama, please note.

And the triple pillars? Well, one is Mr Assad, of course. The second is the crackpot Mr Ahmadinejad. And the third? It was once President Bush. Who will take his place? President Assad must have enjoyed his Iranian caviar.