Yesterday in Geneva, Kerry and Lavrov at last found some common ground, agreeing Syria must give inspectors access to all chemical weapons ahead of their complete destruction or removal by mid-2014.
In a joint press conference, Kerry and Lavrov outlined a six-point framework under which Syria must hand over a full list of its stockpile within a week. If Syria fails to comply, the deal could be enforced by a UN resolution backed by the threat of sanctions or force.
"There can be no room for games. Or anything less than full compliance by the Assad regime," Kerry said. Both diplomats stressed that if Syria failed to comply, a resolution would be sought under Chapter VII of the UN charter, which allows for the use of military force.
The latest agreement between the US and Russia could open the way to reviving an earlier plan to hold a wider international peace conference aimed at ending Syria's brutal two-and-a-half year conflict.
Had Kerry and Lavrov failed to find any common ground in Geneva it would have meant going back to square one, leaving the US with little option but to re-consider the use of weapons to punish the government of President Bashar al-Assad for using illegal chemical weapons against his own people in a military operation in Damascus.
As Kerry left Geneva for talks today in Jerusalem with Israeli leader Benjamin Netanyahu on the final status negotiations between the Israelis and Palestinians, State Department officials were guardedly optimistic that there was enough agreement between the two sides to justify further talks. However, they warned "there is still a long way to go and still a raft of differences." The message seemed to be that at least Kerry and Lavrov are still talking: what a difference a week has made in this most intractable and alarming of recent international crises.
It was the week when the world went to the brink, hesitated and then seemed to pull back. Last weekend everything pointed to the probability of a US-led missile strike on Syria to make it clear to Assad that the world would not tolerate his behaviour.
The weapons systems were all in place, the targets had been chosen, US diplomats had pulled out of neighbouring Lebanon and commanders were on stand-by for the orders that would launch the assault. All that stood in the way was President Barack Obama's address to the American people last Tuesday evening, followed by a vote to gain the backing of Congress and the production of reliable evidence from UN weapons inspectors.
It was all systems go. Then, unexpectedly and against all the odds, the moment passed and diplomacy was given another chance. Assad blinked and, backed by Russia, announced he was prepared to hand over his stocks of chemical weapons and make himself accountable to the international community.
Instead of bombs falling on the streets of Damascus, a bombshell was dropped on the White House, where Obama had just finished telling the people of the US that "with modest effort and risk, we can stop children from being gassed to death, and thereby make our own children safer over the long run", adding: "I believe we should act. That's what makes America different. That's what makes us exceptional."
Obama's words were firm and principled but the fact is that he was quickly trumped by President Vladimir Putin, who brought to the table the tangible offer of a deal that seemed to be workable. If any moment revealed how Assad and his main ally Russia had regained the initiative in the stand-off with the US, it was the sight last Thursday of Syrian forces taking control of the hilltop town of Maaloula some 35 miles to the north-east of Damascus. Earlier in the day, the Free Syrian Army (FSA) and members of the jihadist al-Nusra Front had occupied the small, precipitously situated town for several hours but were then forced to withdraw after their positions had been bombed by Syrian government warplanes.
In a carefully orchestrated move, freshly uniformed Syrian soldiers were on hand to be interviewed in the streets of Maaloula by Western television crews. Once in front of the cameras they were free to express their relief at having "saved" this iconic Christian site, many of whose 3500 inhabitants still speak Western Aramaic, the ancient language used in the time of Jesus Christ. One of them seized the opportunity with a withering yet obviously rehearsed comment: "We gave you St Paul; you gave us terrorism."
The full story of the dramatic "liberation" of Maaloula remains unclear, but one fact stands out. In the subsequent television footage much was made of the town's Christian identity. No-one could escape the message: Assad's forces were making a stand against infidel rebels representing fundamentalist Islam who were busily desecrating Christian shrines. Even though that turned out not to be strictly true, it was a powerful communication to send to the God-fearing heartlands of middle America ahead of Obama's agonising about whether or not to bomb Syria. Judging by what happened next, the footage cannot have harmed Assad's cause.
Maaloula is place that is not easily ignored or forgotten. The last time I visited it was in 2011 at the very beginning of the civil war, and at the time its largely Christian population was determined to keep out of the fighting by not taking sides. Now the town is firmly on the frontline and its people are being used as a diplomatic punch bag by both sides. The town has become a symbol of the deep divisions and suspicions that underpin the Syrian conflict and have made it such an important tool in the propaganda battle being fought not just between Assad and the FSA but also between Russia and the US.
As long as Assad's forces held Maaloula, they appeared to be standing up for the forces of moderation against the threat of Islamic fundamentalism in the shape of the al Qaeda jihadists who support the FSA. In turn the fighting in Maaloula begged the question: why would the US want to punish a country for protecting a palace of pilgrimage, especially when Assad was offering to hand over to the international community the supplies of chemical weapons that may or may not have been used against the Syrian people?
Coupled with a slick interview the Syrian president gave on the same day to a US television network and an equally smooth article signed by President Putin in the New York Times, Maaloula became an unlikely symbol of how Assad and his Russian ally had regained the diplomatic initiative last week.
There was more to come. On Friday, at the end of a fraught week, Syria announced it had become a full member of the global Chemical Weapons Convention, a move it had promised as part of the wider Russian plan to avoid US military action. Once again Putin was quick off the mark, announcing that it was "an important step towards the resolution of the Syrian crisis." China's President Xi Jinping threw his weight behind the Russian initiative and the Chinese Foreign Ministry said in an a statement released almost simultaneously that it welcomed Damascus's move. This was an important intervention, as Russia and China have been the main stumbling blocks in dealing with the Syrian crisis.
What happens in the coming fortnight will define the outcome of this crisis. For the time being at least, the cruise missiles remain in their silos and will do so until at least the end of the month, when talks will reopen to coincide with the reopening of the UN General Assembly on September 28. Peace of a kind has emerged from this weekend's bilateral talks, but the next round will be less cosy and could founder on whether or not the FSA will decided to attend them.
There is already a good deal of dismay in the rebel camp. FSA commander General Salim Idris and Ahmad al-Jarba, the president of the Syrian opposition, have not only rejected the Russian initiative but have renewed their demands for an immediate US air strike, which they believe could turn the war in their favour. Iran's attitude will also be a factor. Not only is it Syria's main ally in the Middle East and a fellow Shia country, but it regards Assad's regime as an important bulwark against the claims of Saudi Arabia and Qatar, both of which are Sunni and important allies of the US.
Then there is the question of the verification of the alleged weapons stocks. As was seen in Iraq in the 1990s when a similar task was undertaken, this will never be an easy process when the host government is the final arbiter of what can be inspected. It will be doubly difficult in time of civil war. Dismantling and destroying illegal weapons will be equally difficult and time-consuming.
There will also be a high degree of unwillingness to be too helpful on the part of Assad's government and armed forces: as a US military source explained, Syrian commanders have long regarded chemical weapons as "a weapon of last resort and a valued deterrent in Syria's long confrontation with Israel", and they will not want to surrender that advantage.