Top US envoy John Kerry met Russian President Vladimir Putin on Thursday to offer him closer military and intelligence cooperation in the hope of salvaging the stalled Syria peace process.
Ahead of the talks, pessimistic US officials were careful to say the trip was not a last chance for diplomacy to work, but stressed they were running out of patience with Moscow.
The meeting, as revealed in a leaked document published by The Washington Post, was a platform to consider the US military working with Russia against Nusra Front and DAESH. The document called for intelligence sharing to identify leadership targets, training camps, supply lines and headquarters of Nusra Front, al Qaeda's affiliate in Syria.
In exchange, Russia would have to convince or strong-arm its ally Bashar al Assad into grounding his planes and halting attacks on civilians and moderate opposition groups.
However, as the two sat down at the Kremlin, they remained tight-lipped about what actually was on the table for discussion.
"I would like to note our mutual effort in the settlement of conflicts that we deem important to resolve," Putin said, conveying his regards to President Barack Obama.
"My last conversation with President Obama has convinced me that we are indeed striving not only to establish a process of cooperation but also to achieve important results."
Sitting across from him, Kerry, confirmed Obama had found the recent telephone call "constructive.”
"Hopefully we'll be able to make some genuine progress that is measurable and implementable and that can make a difference in the course of events in Syria," he said.
Kerry is also to meet Russian Foreign Minister Sergei Lavrov on Friday.
The US secretary of state declined to comment when asked about the leaked document before leaving for Moscow.
Kremlin spokesperson Dmitry Peskov said he would refrain from comment until Russian officials had heard from Kerry.
Peskov said in general Russia favoured cooperation with the US on Syria. However, RIA news agency quoted foreign ministry spokesperson Maria Zakharova as saying Moscow was not satisfied with the current pace of US-Russia military cooperation.
Off the beaten track
Kerry said Obama and he believed the US and Russia were in a position to make "an enormous difference" in the course of events, not just in Syria but also in Ukraine.
But his diplomatic words could not conceal deep-rooted US concerns; Washington has said two major issues to be addressed were Assad's ceasefire violations and Nusra Front's growing role.
"We need a solution that addresses both of these problems," a senior US official said.
"If we cannot get to a solution that resolves both of those problems we're going to be in a very different place, and the reality is that time is short here," he warned.
"We are here to test in what is pretty much close to the end stage of whether this is going to work, to take a shot with the Russians at whether we can solve those two major problems with the cessation of hostilities and get this back on track," another senior official noted.
US officials downplayed the significance of the military offer, arguing they would have gone after Nusra anyway.
But critics of US policy are bound to see any offer to aid Putin's campaign in Syria – even against DAESH – as a victory for the Kremlin.
Kerry faces some strong opposition against his efforts to woo Russia from US defence and intelligence officials who say Washington and Moscow have diametrically opposed objectives in Syria.
On Thursday, the commander of the US-led coalition battling DAESH, Lieutenant General Sean MacFarland, voiced US military concern about Russia's intentions in Syria.
"I'd be a little leery about giving too much information to the Russians but I fully trust that our government officials understand this and know they'll arrive at something that makes sense," MacFarland told reporters in Baghdad.
Kerry's trip, his second to Moscow this year, comes amid worsening US-Russia relations after tit-for-tat diplomatic expulsions. US has accused Russia of aggressive manoeuvres toward American aircrafts and vessels and what Washington considers a disregard for a cessation of hostilities in Syria, where Russia has bombed US-backed opposition forces.
And there was no sign in Damascus that Assad feels under any pressure to agree to talks on a new government, the next stage in the process if a ceasefire is restored.
Speaking to NBC News in Damascus, Assad insisted Putin and Russian Foreign Minister Sergei Lavrov had never raised the issue of his departure or a political transition.
"Only the Syrian people define who's going to be the president, when to come, and when to go. They never said a single word regarding this," he insisted.
Moscow and Washington, and the 22-nation contact group they co-chair, have called for a nationwide ceasefire and Geneva-based talks on a "political transition."
A landmark partial ceasefire brokered in February – which did not include DAESH or Nusra – has since all but collapsed amid continued heavy fighting.
UN Syria envoy Staffan de Mistura urged Moscow and Washington to push for a resumption of the talks next month.
Mistura said the talks "have a target date of August" and need to be "a credible beginning of a roadmap towards a political transition."
US offer to Russia
Russian forces are currently fighting in support of Assad's regime against a variety of opposition factions while a US-led coalition focuses its fire on DAESH.
The Washington Post, citing a draft proposal from the United States, reported that the US and Russia could set up a joint command and control centre in the vicinity of the Jordanian capital Amman.
The United States and Russia would establish separate headquarters and a shared coordination office, where they would deploy senior officials, intelligence personnel and experts in strike planning and targeting.
They would decide on a date to simultaneously begin strikes against Nusra Front targets and to stop all Syrian military air activities in designated areas, except for non-combat purposes and against areas where Nusra Front has acquired territory.
The proposal also allows for Russia to use air power to defend Syrian forces from attack from Nusra Front within a designated area, if agreed in advance with the United States.
Syria's civil war erupted in 2011 when Assad brutally suppressed anti-government demonstrations. The situation has since then evolved into catastrophe that has left more than 470,000 dead according to the Syrian Center for Policy Research.
Efforts to bring an end to the war have taken on greater urgency since the emergence of DAESH, which seized control of large parts of Syria and neighbouring Iraq in mid-2014.