Developments are rapidly taking place, some behind the scenes, which will have a significant impact on the Syrian conflict and the broader war against Isis.

In the last 48 hours, the Turkish premier, Ahmet Davutoglu, effectively confirmed what we have known for a while, that his country and the US are planning to set up a buffer zone across the border. Then, Jabhat al-Nusra, the al-Qaeda affiliate in Syria, announced that it will withdraw fighters from the projected area of the buffer zone. Today, the Americans began their first air strikes against Isis from the Incirlik air base. Washington’s use of the Turkish base was part of the deal with Ankara over the buffer zone.

Also this week, on Tuesday, Adel al-Jubeir, the Foreign Minister of Saudi Arabia – the main backer of the Syrian rebels, met Sergei Lavrov, his Russian counterpart – the main backer, along with Iran, of the Assad regime. The talks in Moscow had followed another meeting, the first between senior Russian, American and Saudi officials over Syria. The Russians briefed the Syrian regime, whose Foreign Minister Walid al-Moallem, then flew for talks in Oman, a country which has successfully retained good relations with both Iran and Saudi Arabia.

All this is taking place against the background of the Syrian regime suffering reverses and admitting that it is doing so. Three weeks ago President Assad, in a televised speech, took the unprecedented step of describing how his troops have had to give up territory and retrench. He announced amnesty for 70,000 deserters and those who have avoided the draft. His 300,000-strong force has been cut in half by casualties and desertions since the start of this vicious war. At least 80,000 soldiers and Shabiha, the militia of the Alawite community from which the ruling elite are drawn, have been killed.

Regime forces have been collapsing back into defensive lines at several places around Alawite strongholds. Senior officers, according to the latest batch of deserters, accept that the north, especially around Idlib province, is now lost unless there is a dramatic change of fortune.

The withdrawal of Jabhat al-Nusra from the designated buffer zone, 60 miles deep, stretching from east of Aleppo on the Euphrates, Turkish officials say, would allow “moderate” rebels to establish themselves shielded by American air power and, in an emergency, the Turkish army.

Much, however, depends on the definition of “moderate”. The Turks are said to favour Ahrar al-Sham, which had been fighting in the Aleppo area with some success. The group is part of the Jaysh al-Fatah coalition, which has been responsible for the push against regime forces. Ahrar al-Sham, however, has co-operated with Jabhat al-Nusra and, until two years ago, Isis.

The Western-backed Free Syrian Army remains relatively powerless and a Pentagon scheme to train fighters has yielded only around 50 so far. A plan of General John Allen, Barack Obama’s envoy to the rebels, to create a “Sunni Awakening” using tribal fighters, modelled on a force in Iraq during the US occupation, is still at an embryonic stage.

Turkey has long pressed for a “no-fly zone” across the border. The Americans did not agree with that term because it may have involved having to shoot down regime aircraft, and Washington does not want a conflict on two fronts while still combating Isis. It has agreed, instead, to having a “safety zone”.

Nevertheless, it will be the first time since the Syrian uprising began four years ago that foreign powers have seized territory inside the country and the new channels to Damascus may ensure that President Assad accepts that loss of sovereignty just as he has accepted the American-led air strikes in Syria.

The likely fate of President Assad has once again become a source of discussion among the powers. The Western demand that any settlement must include his removal is no longer so strident with the rise of Isis and worries about a vacuum if the Syrian leader goes. A senior British defence official, whose remit includes Syria, said this week: “We have spent almost five years now trying to find a viable alternative, and we have failed.” Conversely, Moscow, and even Tehran, may not be as adamant about President Assad staying on as they had been in the past.

During the second round of talks on Syria, in Geneva 19 months ago, another UK official dealing with Syria said the “Russians will throw Assad under a bus when it suits their purpose”. It has not, obviously, suited Moscow’s purpose, so far, to do so. But life after Assad is said to have been discussed by the Americans and the Russians. “The problem remains the same”, according to an US official, “finding the right group, or individual, who could take over and ensure the country does not just disintegrate.”

But Assad is no longer the only massive obstacle to finding a solution to the conflict; there is deep concern in the West about Turkey’s continuing ground and air attacks against the Kurds, the PKK, and, in Syria, YPG. Mr Davutoglu reiterated on Tuesday that his government regarded them as “terrorists”. The Americans, on the other hand, regard the YPG as the most reliable ally on the ground against Isis and provide them with air support.