London (AFP) - With time running out for the besieged people of Aleppo and for a US administration with barely three months left on the clock, John Kerry is looking for new ideas.
In two days of international talks over the weekend, Washington's chief diplomat continued to bang his well-worn drum for a renewed ceasefire in Syria's ugly conflict.
But -- having hit a brick wall in efforts to convince Russia to help its US rival impose a ceasefire -- he made it clear that he wants other countries to play a bigger role.
On Saturday in Lausanne, Syria's neighbours -- some of them enemies among themselves, others with their own agendas -- were brought back to the table and pumped for suggestions.
Then on Sunday in London, US allies from Europe and the Gulf were pressured to come up with ideas of their own.
Talk is of a new track, but very little concrete has emerged. As Syria's civilians face starvation and bombardment, world capitals are doing what Kerry dubbed "brainstorming".
And the US diplomat did not hide his frustration at setting off once again down the track of finding a ceasefire plan that Russia and Syria would accept and implement.
This plan will be put to the test -- "yet again, but in a different way, yet again" –- in order to find out whether it's possible to pause the fighting long enough for peace talks.
"Now, our job is to exhaust those possibilities. That's what we're trying to do," Kerry said, standing alongside a more ebullient British Foreign Secretary Boris Johnson.
- Calls for action -
Back in Washington, President Barack Obama has made no secret of his reluctance in his last weeks in office to commit US military power to the battle to destabilize Bashar al-Assad.
But Russia has been no more coy about its determination to shore Assad up even to the extent that its war planes are engaged in the bombardment of rebel-held eastern Aleppo.
Saturday's meeting in Switzerland brought together the powers which influence the armed factions, and ideas were floated to separate Al Qaeda-linked extremists from moderate groups.
Then on Sunday, with the Europeans, Kerry discussed pressuring President Vladimir Putin and showing him that Russia's interests are best served by a ceasefire and peace talks.
Johnson and Kerry both sharply played down the idea of military force, but both said new sanctions were possible and the British minister floated the idea of war crimes charges.
"These things will eventually come to bite the perpetrators of these crimes. And they should be thinking about it now," Johnson warned, bristling at reporters' questions.
Kerry too expressed frustration at calls for action.
"I haven't seen a big appetite in Europe for people to go to war. I don't see the parliaments of European countries ready to declare war," he told British reporters.
- Mass grave -
A secretly taped conversation released last month confirmed what had been widely assumed that Kerry had argued for US air strikes against Assad to give his diplomacy more bite.
Obama rejected the plan, and Kerry threw himself into the search for an international negotiated solution.
"So we are pursuing diplomacy because those are the tools that we have, and we're trying to find a way forward under those circumstances," he said on Sunday.
"Easy to say, where's the action? But what is the action?"
One day before Kerry's visit to Lausanne he had stood at the genocide memorial in the Rwandan capital Kigali and pondered a mass grave holding 250,000 of the victims of the 1994 genocide.
A similar number of civilians and -- according to Johnson -- between 10,000 and 11,000 opposition fighters are trapped in eastern Aleppo facing daily indiscriminate bombardment.
If they are to be saved, it seems to be out of American hands.
And Johnson, having been asked for ideas, appealed to Assad and his "puppeteers" Russia and Iran to display one quality that has been lacking in Syria's five-year carnage.
The British minister praised Kerry for his efforts to convince Moscow and Tehran to halt the bombing, but admitted: "It's really up to them now to listen and to show mercy."