Russian warships and aircraft are in place, as are a contingent of Iranian and Hezbollah militias; the Syrian regime has been reinforced; key strategic points have been seized: all signs that the long-awaited battle for Aleppo is due to start very soon.

But recapturing the opposition-held half of what was once Syria’s largest city and commercial capital is just the next step in Moscow’s mission. It will not end either when Isis loses Mosul and Raqaa, the capital of its “caliphate”. The aim, say senior Kremlin officials, is ensuring that al-Qaeda affiliate Jabhat al-Nusra and its allied rebel battalions are finished as a threat.

The coalition including al-Nusra, of which several rebel groups supported by the West are also members, has been the most effective against the regime and has also, at times, fought Isis. There have been repeated charges by the US, UK and European allies that Russian bombing of the rebel coalition has been aimed at destroying, not just the Islamist extremists, but all resistance against Syrian President Bashar al-Assad,

The American criticism is likely to end with the election of Donald Trump who has spoken publicly of his admiration for Vladimir Putin and expressed support for the Russian leader’s actions against “terrorists”. The US President-elect has already stated that he is likely to abandon support for the “moderate” opposition saying: “My attitude is that you’re fighting Syria: Syria is fighting Isis and you have to get rid of Isis. Russia is now totally aligned with Syria. Now we are backing rebels against Syria and we have no idea who these rebels are.”

Al-Nusra had been among Islamist groups which had received backing from the Gulf states but it is officially classified as a terrorist organisation by both the US and Russia. It recently declared, in response it is believed to Qatari pressure, that it was severing links with al-Qaeda and renaming itself Jabhat Fateh al-Sham.

The Russian ambassador to the UK, Alexander Yakovenko, told The Independent: “Jabhat al-Nusra is a terrorist organisation which is part of al-Qaeda. They changed their name recently, but they remain a part of al-Qaeda. Then we have all these rebel groups which are supporting al-Nusra. Some of these groups are supported by the West, but they work with al-Nusra.

In pictures: Aleppo bombing Show all 14 1 /14 In pictures: Aleppo bombing In pictures: Aleppo bombing Bombing in Aleppo Smoke rises after airstrikes on the rebel-held al-Sakhour neighborhood of Aleppo, Syria April 29, 2016. Reuters In pictures: Aleppo bombing Bombing in Aleppo A Syrian family runs for cover amid the rubble of destroyed buildings following a reported air strike on the rebel-held neighbourhood of Al-Qatarji in the northern Syrian city of Aleppo, on April 29, 2016. AFP/Getty Images In pictures: Aleppo bombing Bombing in Aleppo A man reacts as he stands on blood stains at a site hit by airstrikes in the rebel held area of Aleppo's al-Fardous district, Syria, April 29, 2016. Reuters In pictures: Aleppo bombing Bombing in Aleppo The damage of the airstrikes in the rebel-held area of Aleppo on April 28 Reuters In pictures: Aleppo bombing Bombing in Aleppo The damaged the Medecins Sans Frontieres (MSF)-backed al-Quds hospital after it was hit by airstrikes, in a rebel-held area of Syria's Aleppo Reuters In pictures: Aleppo bombing Bombing in Aleppo Syrians evacuate an injured man amid the rubble of destroyed buildings following an air strike on a rebel-held of Aleppo on April 29, 2016. AFP/Getty Images In pictures: Aleppo bombing Bombing in Aleppo People inspect the damage at a site hit by airstrikes, in the rebel-held area of Aleppo's Bustan al-Qasr AP In pictures: Aleppo bombing Bombing in Aleppo A man leads a woman in tears and child out of the scene after airstrikes hit Aleppo AP In pictures: Aleppo bombing Bombing in Aleppo Civil defence members search for survivors after an airstrike at a field hospital in the rebel held area of al-Sukari district of Aleppo Reuters In pictures: Aleppo bombing Bombing in Aleppo A Syrian boy is comforted as he cries next to the body of a relative who died in a reported air strike in the rebel-held neighbourhood of al-Soukour in the northern city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo A Syrian family walks amid the rubble of destroyed buildings following a reported air strike in the Bustan al-Qasr rebel-held district of the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrian civil defence volunteers and rescuers remove a baby from under the rubble of a destroyed building following a reported air strike on the rebel-held neighbourhood of al-Kalasa in the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrians help a wounded youth following an air strike on the Fardous rebel held neighbourhood of the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrian civil defence volunteers evacuate people from a damaged building following a reported airstrike in the rebel-held neighbourhood of Tareeq al-Bab in the northern city of Aleppo

“How can we have a proper ceasefire in Aleppo when al-Nusra, who the Americans themselves say is a terrorist group, carries out attacks on government forces and these so called ‘moderate’ groups join them in doing that. Al-Nusra is a big problem, but as far as we are concerned, all the groups who break the ceasefire and carry out killings are terrorists.”

A former senior Russian adviser to the Kremlin on foreign affairs commented: “There were media reports that the Aleppo operation somehow depended entirely on the timing of the American election. But, in reality, it was always going to be when all the logistical factors were in place. Of course, the outcome of the election offers new opportunities going forward for both the Russian Federation and the United States for a coordinated long-term policy to deal with terrorism.

“It is not logical to focus just on Isis and not al-Nusra, we have been very clear on that. They are two sides of the same coin, they carry out the same kind of terrorist action. There is good intelligence showing that Isis fighters are joining al-Nusra, and al-Nusra fighters have joined Isis in the past. Then we have the other groups who join al-Nusra in attacking government forces, attacking civilians. How can you separate them? Even the Americans have begun to understand that.”

John Kerry was candid during a visit to London a fortnight ago about the difficulties the West has had in stopping the “moderate” groups from fighting alongside al-Nusra. “When al-Nusra decides to attack the regime during a ceasefire the regular opposition gets swept up with them and then all of a sudden your ceasefire starts to shred.”

The US Secretary of State added that the Assad regime also played its part in the breakdown of ceasefires by bombing other rebel groups while claiming to attack Isis and al-Nusra. “So the opposition then get angry and say he is not showing good faith, because he is not. And then it spirals downwards.”

Al-Nusra has offered rewards to other groups for the capture of Russian soldiers and airmen. One of its leaders, Abu Ubaid al-Madani, who speaks Russian, has appeared in a video saying all Russian captives would be killed. Abu Mohammed al-Julani, the group’s overall commander, had asked Muslims from former Soviet Caucasus to carry out bombings against Russian civilian targets.

The Russians and the regime will, however, have a difficult job in tackling al-Nusra and its allies. Although Isis became the most powerful of the rebel groups, spreading its territory from Syria to Iraq with breathtaking speed, it also became isolated from others in the opposition and experienced large-scale desertions.

Abdulkarim al-Nasri, who was, until recently, a fighter with Ahrar al-Sham – a group backed by Turkey which has openly allied itself with al-Nusra – said: “Al-Nusra is certainly not the same as Daesh [Isis]. That is the view of most of us who have fought against Assad and they will join al-Nusra in fighting the Russians.

“We know that Trump will betray us, we knew the Americans were always going to betray us. So the time for listening to false promises from America and Europe is over; people have no other choice but to fight and the fight now is in Aleppo.”

Rebels and civilians in eastern Aleppo have received a warning from the regime, the latest of a series, telling them they have 24 hours to leave Aleppo. A Russian fleet of eight ships led by the aircraft carrier Admiral Kuznetsov, and including the nuclear-powered battle cruiser Pyotr Velikiy, are now in seas off Syria, ready, said the commander of the aircraft-carrier, Sergei Artamonov, to fulfil its task.