Any serious chances of salvaging a political deal in Syria lie with John Kerry and Sergei Lavrov. Only when the US and Russia are in full agreement and working together is there any chance of corralling the regime of President Bashar al-Assad and the disparate forces on the ground to engage in a political process.
But to date, such cooperation has been momentary, not lasting.
The US-Russia talks have thus far failed to deliver, and few gave much credence to the Saudi foreign minister's recent statement that a deal could still happen within 24 hours. Russian President Vladimir Putin as yet has felt in no mood to acquiesce to American wishes for a deal, including an agreement for a no-fly zone in northern Syria.
This is the center stage to the sideshow of London's Syria meeting earlier this week. Understanding it helps to explain why both Europe and the US have been pushed to the periphery on Syria, at least for the time being.
Two aspects of the conflict have changed recently. First, the recognized opposition in Syria appears to have shifted its position on President Assad. Second, the dramatic domestic politics in Turkey have drastically altered its relationships with both the West and Russia.
On Wednesday, the High Negotiations Committee (HNC) from the Syrian opposition presented to the Friends of Syria their "Executive Framework for a Political Solution" for Syria.
This was a thin rehash of their existing positions of pushing for transition, democracy and human rights. Its lack of clarity and detail reflect the international divisions and rivalries in the multifarious opposition groups.
Buried within the published HNC plan was one key detail: The opposition has abandoned calls for Assad to step down as a precondition for negotiations. His departure is reduced to a negotiating position. It envisages Assad and his "clique" leaving after a six-month negotiating phase but at some point during a subsequent 18-month transition stage.
This reflects the realities five-and-a-half years into the Syrian conflict. The regime is well entrenched in western Syria, buttressed by Russian and Iranian military and financial muscle. The HNC has few allies and a diminished political base; squeezed between the regime and the hard-line Islamists.
European powers are anxious to ensure that the option of the "moderate" opposition does not disappear. The HNC was not a sideshow at this London meeting -- as they have been in past Friends of Syria events -- but the main course. The intended message was that there is still a choice that does not include Assad or the hardliners.
Saudi Arabia and the other Gulf states are also becoming increasingly frustrated. Should Turkey back away from fully supporting
opposition groups in northern Syria then their options are limited? Supplying weaponry to armed groups may prove tougher without the active consent of Ankara and access to the Syrian border.
Meanwhile, the US focus seems to have moved. Secretary of State John Kerry only joined the London meeting by video conference. For some time smashing ISIS in Iraq and Syria has been the priority, not shifting Assad nor thwarting Russian ambitions.
The Obama administration is winding down, and Russia and the regional powers know it. Russia, Iran and Turkey are busy trying to rearrange the bloodied jigsaw of Syria for a grand fait accompli by January 20, 2017, and the inauguration of the next US president. Few doubt that either a President Clinton or a President Trump will rattle the US drums in the Middle East more vigorously than the current incumbent.
Events on the ground are confirming that the message has reached Syria. A confident, energized regime and a determined Russia feel no fear in dropping incendiary bombs on civilians, bombing hospitals and possibly even using chlorine. It's clear what the punishment is for areas hosting rebel groups. Around Damascus, suburbs like Daraya have effectively surrendered to the regime after enduring years of siege.
Turkey has also shifted, terrified that the Kurds in Syria will achieve a degree of political independence. As the talks in London progressed, the Turkish Deputy Prime Minister said that Turkish forces may penetrate even deeper into Syria.
The underlying theme is that Turkey might agree to Assad remaining in power in return for active repression of Kurdish ambitions. The Syrian air force duly bombed Kurdish areas in August, a message Turkish President Recep Tayyip Erdogan would have picked up immediately.
For the remainder of the year, all eyes will therefore be sharply focused on the Russian, Iranian, Turkish rapprochement. The semi-patched up Putin-Erdogan relationship is fragile, but it's based on a mutual desire to spite Obama and an agreement on the territorial integrity of Syria -- in Turkish terms, denying Kurds any autonomy. If this happens, the losers will be the Kurds and the Syrian opposition.
Many states are anxious to prevent any Russian-Turkish-Iranian project for Syria. But in a few months' time, the picture may change again -- as it always has with this Syrian conflict.
These three powers may have a temporary alignment of interests, but their mutual distrust runs deep and a falling out is highly likely. The question is, have the US, Britain and the rest of Europe been pushed too far to the edges of this conflict to resolve it?
Chris Doyle is the director of the Council for Arab-British Understanding, a London-based NGO. The opinions expressed in this article belong to the author.