Bashar al-Assad could remain as Syrian president for up to six months during a transition process as long as his sponsors Iran and Russia agree to require his eventual departure, according to the UK foreign secretary.

Philip Hammond also repeatedly stressed that the aim of any British involvement in military action in Syria would be limited to disrupting Isis in Raqqa, northern Syria, and would not be to change the balance of power in the deadlocked four-year civil war.

Hammond said there was no intention for Britain to get “involved in complex three-way fights in north-west Syria where regime forces and other forces are involved”.

He added: “What we are looking at are Isil command and control nodes around Raqqa from which it has supply lines running north. We are unable to attack those command and control nodes and supply lines. The military logic drives us to believe there could be utility to have greater freedom.”



Downing Street is making a concerted effort to explain to MPs that the focus of a military campaign inside Syria would be to defeat Isis and so protect the democratically elected government in Iraq, rather than to produce regime change in Syria.

Two years ago David Cameron was accused of lacking a clear set of military objectives when he lost a Commons vote on action to defeat Assad’s regime. This time he is clearly working to show that the government has a limited, legal and achievable strategy to defeat Isis and defend Iraq.

Hammond said: “The objective is to defeat Isil and that means we have to get to the controlling brains. At the moment we are attacking an enemy in Iraq and if we formed the judgment that this air-based campaign was more efficacious if we attacked Isil in Syria, we would ask parliament.

“The logic of extending our mandate to cover Isil targets in Syria would be very clearly a logic in support of the mandate we have in Iraq for the collective defence of that country.”

He said there was no sign at present that either Iran or Russia was prepared to abandon Assad, but argued there was no military solution that would lead to victory either for his regime or his opponents.

He said Britain was prepared to be pragmatic in discussing a transitional plan lasting months. “We are not saying Assad and all his cronies have to go on day one,” Hammond said. “What I am not prepared to discuss is what I understand to be the Russian and Iranian position, that we need to move to elections in Syria and it will be for the Syrian people to decide in those elections whether Assad should remain as their president.

“That is not an acceptable position. The international community cannot, in my view, facilitate and oversee a set of elections in which somebody guilty of crimes on the scale that Assad has committed is able to run for office. That has to be clear. He cannot be part of Syria’s future.”

He denied Assad was the glue holding Syria together. “This is going to have to be a decision by the key players in Syria – Iran and Russia – deciding to call the shots with the Assad regime and make it clear that there has to be change,” he said. “Russia and Iran can have a discussion today, make a phone call to Damascus tomorrow.”

He rejected the argument that the western coalition should join with Assad in fighting the common enemy of Isis. “Our analysis of the problem is that Assad is a recruiting sergeant for Isil and any suggestion that western powers were prepared to work with Assad in the defeat of Isil would redouble that recruiting sergeant effect,” he said.

Hammond acknowledged that each of the players in Syria, including Turkey and Saudi Arabia, had a different agenda. “We are only going to move forward if we can find common threads that everyone can sign up to.”

He said he hoped the recent nuclear deal with Iran and the reopening of the UK embassy in Tehran might help strengthen the moderating forces in that country. He said efforts to train the Free Syrian Army had “taken us longer to get off the ground than we would have liked”, but he denied that fewer than 100 troops had been trained.

Despite various military setbacks, Hammond said, the intervention in Iraq had stopped Isis stone dead and prevented them travelling down the rivers to Baghdad. But he accepted it was unlikely that Mosul could be recaptured until next year, saying it was a complex and fluid position.

Earlier on Wednesday during prime minister’s questions, Cameron appeared to open the door further towards British military action in Syria.

“Assad has to go, Isil has to go. Some of that will require not just spending money, not just aid, not just diplomacy but it will on occasion require hard military force,” he told the Commons.

• The headline of this article was corrected on 9 September 2015 to say that Philip Hammond is the foreign secretary, not the defence secretary as an earlier version said.