According to de Mistura, there had been some progress at his meeting Saturday in Lausanne, Switzerland, with other top diplomats. However, he emphasized a need to build on that progress in order to avoid war-ravaged Aleppo becoming like Darayya or Moadamiyah, two of the country’s besieged cities.

“Aleppo,” he said on Monday, “has a special symbol,” and he hoped that in addition to the discussions in London, the one on Monday in Europe would be a show of unity. Some 275,000 people are in eastern Aleppo, and the western part of the city has also suffered great losses.

On the matter of talks, which he has been facilitating in Geneva, the Special Envoy expressed doubts about being able to have “regular normal discussions” while the city of Aleppo is under bombardment, 100,000 children are stranded, and no humanitarian aid has been able to get through for more than a month.

de Mistura maintained that while he remains determined, he is “worried about the fact that if we miss some type of opportunity to make a change, history will judge us.”

The battle for Mosul has come under global media attention in the past 24 hours – something that the Special Envoy is concerned could confuse the priority of Aleppo: “If the world is watching Mosul, Aleppo should not be forgotten.”

The UN estimates that five years on, the Syrian conflict has driven more than 4.8 million refugees to neighbouring countries, hundreds of thousands in Europe, and displaced 6.6 million people inside the Syria against a pre-war population of over 20 million. Well over 250,000 people are believed to have died and much of the country’s infrastructure has now been ruined.

According to the UN Office for the Coordination of Humanitarian Affairs (OCHA), in spite of a slight reduction in attacks that lasted for two days last week, by the end of the week an up tic in hostilities, including airstrikes on eastern Aleppo, led to many casualties and damage to civilian property.