A meeting of the international coalition against Isis has ended in London with a declaration that the jihadists, fighting for their Iraqi stronghold in Mosul and facing an impending assault on Raqqa, their ‘capital’ in Syria, will soon be defeated.

But the meeting of 14 states took place against a sombre background of continuing recriminations over the impotence of the West in face of the brutal assault on Aleppo by the regime of Bashar al-Assad and its Russian and Iranian backers, and the uncertainty about the policies on Syria that Donald Trump will bring when he takes over at the White House.

The shadow of what is happening in Aleppo continued to dominate focus on Syria as the Isis conference was taking place. Boris Johnson summoned the Russian and Iranian ambassadors to the Foreign Office to express the government’s condemnation of their role in the operation.

Afterwards the Foreign Secretary said: “Both Russia and Iran have failed to uphold their obligation under international humanitarian law, specifically by failing to facilitate the delivery of humanitarian aid during the months when eastern Aleppo was besieged. They deserve no credit for the fact that an evacuation appears to be underway today. Having inflicted such suffering on the people, Iran and Russia cannot expect praise for allowing some people to escape at the final hour”.

During a House of Commons emergency debate over Aleppo earlier this week, George Osborne acknowledged that “this tragedy was created by a vacuum of Western leadership, British leadership”. It is American leadership which is the crucial factor and Mr Trump has already signalled that he wants to end support for Syrian rebels. The President-elect, who has publicly declared his admiration for Vladimir Putin, views Russia as an ally while the US-backed rebels regard it as an enemy state on which President Assad depends for his survival.

Defence Secretary Sir Michael Fallon urged people not to jump to conclusions over Mr Trump’s “campaign rhetoric” and wait to see what actions the new administration takes, stressing that Isis presented a “global threat”. He maintained: “I have no doubt that the next US administration will step up to its traditional role of global leadership”.

Aleppo before the Syrian Civil War Show all 12 1 /12 Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man crosses a street in Aleppo, December 12, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A vendor sits inside an antique shop in al-Jdeideh neighbourhood, in the Old City of Aleppo, December 12, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A view shows part of Aleppo's historic citadel, overlooking Aleppo city, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A view shows part of Aleppo's historic citadel, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Visitors walk inside Aleppo's Umayyad mosque, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk inside the Khan al-Shounah market, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man walks past shops in al-Jdeideh neighbourhood, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk along an alley in al-Jdeideh neighbourhood, in the Old City of Aleppo, Syria Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War Visitors tour Aleppo's historic citadel, Syria December 11, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A general view shows the Old City of Aleppo as seen from Aleppo's historic citadel, Syria December 11, 2009 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War People walk near Aleppo's Bab al-Faraj Clock Tower, Syria October 6, 2010 Reuters Aleppo before the Syrian Civil War Aleppo before the Syrian Civil War A man stands inside Aleppo's historic citadel, overlooking Aleppo city, Syria December 11, 2009 Reuters

US Defence Secretary Ash Carter, standing beside Sir Michael at a press conference in London, could give no such guarantee. “I can’t speak for the next administration” he said. However, he continued that the “coalition campaign was logical, made sense” and thus hoped that “logic will recommend itself to the future leadership of the United States, even as it has recommended itself to the current leadership.”

According to senior diplomats, Mr Carter, on his last trip to London in his post, has sought to reassure his European counterparts during the visit that his successor at the Pentagon, General James “Mad Dog” Mattis, will be a counterweight to those within the Trump administration who are expected to press for disengagement from Syria or are deemed to be close to Moscow.

A British team to train opposition fighters has arrived in Syria and Sir Michael announced a six month extension to the deployment of British troops carrying out infrastructure construction at an airbase, al-Asad, in Iraq. RAF warplanes, he said, were carrying out attacks in support of a rebel group, SDF (Syrian Democratic Forces) on approach routes to Raqqa.

George Osborne: We're partially responsible for Syrian crisis

Sir Michael said he had been assured that the rebel force heading for Raqqa was predominantly Arab. But although the SDF has Arabs in its ranks, it is Kurdish led and has been involved in clashes other Sunni Arab groups from the Free Syrian Army (FSA) including a faction supported by Turkey which has sent thousands of troops, backed by armour and aircraft, into northern Syria.

It is unclear where the rebels trained by the British will fit into a violent mixture of competing groups which are trying to seize Raqaa while fighting each other as well as Isis. The offensive is being carried out by Sunni Arab and Turkmen fighters of the FSA with Turkish support ; the SDF and the Kurdish militia YPG with American advisors and air support and the regime’s army with Russian, Iranian and Hezbollah backing.