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On Wednesday, the Syrian opposition gathered in London to unveil its vision for a transition in which Bashar al-Assad and his coterie would be moved aside as part of a peace process to end the war in Syria. The unveiling of the framework was an important milestone for the opposition, but it appeared divorced both from events on the ground and US-Russia discussions.

The reason for this is simple. The London meeting was timed to follow an expected agreement at the G20 meeting in China between the US and Russia over a truce in Aleppo and the targeting of armed groups. This was to be the trigger for a fresh round of diplomatic efforts to negotiate an end to the Syrian conflict.  But the US-Russian agreement never happened, leaving the opposition once again in limbo.

John Kerry is once again meeting his counterpart Sergei Lavrov today to attempt to push through the deal. Yet, the gaps remain significant between the two sides.   

Following the Russian intervention last September, the UN has been marginalised in the diplomatic process, with negotiations over Syria essentially conducted between Washington and Moscow.  In February, the two powers brokered a "cessation of hostilities" which did deliver some respite for civilians in its first weeks as many fighting groups observed its terms, but was soon widely violated.

Moreover, the agreement has failed to secure sustained humanitarian access to besieged areas and those most in need.

In recent months, there has been a sustained attempt by Kerry to revive the cessation of hostilities as a pathway to the implementation of UN Security Council Resolution 2254, and breathe life into a now absent peace process. 

Following the Russian intervention last September, the UN has been marginalised in the diplomatic process

The approach has been to focus on the elements of the conflict upon which Russia and the US can agree; namely, cooperating over the targeting of the Islamic State (IS) and Jabhat Fateh al-Sham, formerly known as Jabhat al-Nusra. 

In keeping with the pattern of negotiations up until this point, some assert that Russia has been stalling Kerry over an agreement, while its aligned forces seek to change the military balance in their favour.

In July, the White House tipped its hand by a draft of the agreement it would like to reach with the Kremlin.  The draft proposed the formulation of a joint military operations centre that would oversee targeting of the two groups, and set a start date of July 31. 

Now, though, events have overtaken it. Following the regime and its affiliates' capture of the last remaining supply route to rebel-held areas of the city, the rebels launched a major counteroffensive in Aleppo on July 31 in which it severed regime supply lines to regime-held areas of the city. 

This resulted in a situation where the east and west of the city were effectively besieged by the regime and the rebels respectively. The regime has since counterattacked once again. At the time of writing, it appears to have reopened its supply lines, although the situation remains fluid. This complicates negotiations over humanitarian access to the city. 

Moscow was either unwilling or unable to secure regime adherence to the cessation of hostilities

If Castello Road - the former rebel artery into Aleppo - is indeed the agreed route for all humanitarian access, then this means it will be internationally protected and will therefore remain under regime control. Meanwhile, rebel-held eastern Aleppo will remain under siege.

Then there is the thorny issue of Jabhat Fateh al-Sham, as it is now known. The leaked document proposed that, for strikes on IS, the US and Russia could act independently, but in the case of Jabhat Fateh al-Sham, both sides would have to agree on the target in advance.

This would reduce opportunities for the Russian military to strike other rebel groups under the premise that they were Jabhat Fateh al-Sham, or that they were in the vicinity of it.

Meanwhile, it was hoped that by clearly designating the areas in which Jabhat Fateh al-Sham were operating, a de facto no-strike zone would be imposed upon the Syrian regime outside of those areas, therefore raising the prospect of bringing an end to the vicious campaign of barrel bombing of many civilian areas.

But Moscow's ability to dictate terms to the Syrian regime often appears overstated. Moscow was either unwilling or unable to secure regime adherence to the cessation of hostilities, let alone an undertaking for the regime to reduce its use of airpower, its pre-eminent battlefield advantage.

Jabhat Fateh al-Sham fought alongside groups that receive US backing in the Aleppo offensive, providing a headache for the White House

It should be seen as no coincidence that Jabhat Fateh al-Sham had rebranded itself, renouncing its affiliation with Al-Qaeda only days before the Aleppo operation was launched. Its fighters formed the vanguard of the offensive in a rare example of rebel unity. 

Analysts have argued that this was a well-calculated move that will embed the group deeper into the opposition and also improve its image among the rebels. The move also complicates any agreement between the US and Russia over the targeting of the group. 

Jabhat Fateh al-Sham fought alongside groups that receive US backing in the Aleppo offensive, providing a headache for a White House whose delineation of groups acceptable to it is likely to become increasingly blurred.

With the clock ticking on the Obama Administration, a major breakthrough is increasingly unlikely as key actors in the conflict look to stall, and attempt to shift the facts on the ground in their favour ahead of the inauguration of a new president. 

At present, the international community is failing to even achieve humanitarian access to those in greatest need in Syria, let alone broker a deal which will bring about a nationwide ceasefire. For Kerry to reach a deal, he is likely to have to make further concessions on the draft leaked to The Washington Post. And even then, if past is prologue, it will be even more difficult to implement. 

Tim Eaton is Research Fellow of the Middle East and North Africa programme at Chatham House. Follow him on Twitter: 

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