The proposal put forward in Parliament to shoot down Russian and Syrian aircraft over Eastern Aleppo in a bid to end the bombardment of this part of the city is wholly unrealistic. The West is not going to risk a war against a nuclear power and its Syrian ally in order to help the 250,000 to 275,000 civilians trapped there. To pretend anything else is empty bombast detached from the realities on the ground. The danger of such wild schemes is that they divert attention from more realistic plans to save the besieged from further suffering and death.

These realities in Aleppo are that the city, once the industrial heart of Syria, has been split between government in the west and rebels in the east since 2012. In the course of this year, the Syrian army and Shia paramilitary forces from Iran, Iraq and Lebanon have surrounded East Aleppo which is being battered into ruins by Russian and Syrian air strikes and shelling. Hospitals and health care centres are being systematically destroyed. There is an economic blockade with UN aid convoys unable to pass through government checkpoints. It is near impossible to cook such food as there is because of the lack of propane gas cylinders and kerosene.

East Aleppo was first fully encircled by pro-government in forces in July when they cut the so-called Castello road in the north of the city which was the last link to rebel areas to the west. The main supply road from East Aleppo to Turkey had been severed in February. A rebel counter-offensive briefly broke through the siege lines in August in the Ramouseh Road in south Aleppo only for the Syrian army and its allies to re-impose the siege in September.

It looks unlikely that the encirclement can be broken by military means. The last time around the rebels suffered heavy casualties put at around 500 dead. The lesson of all the many sieges taking place in Syria and Iraq over the last year – Daraya in Damascus, al-Waer in Homs, Ramadi and Fallujah in Iraq – is that rebel light infantry stands no chance in the long term against heavy air attack directed from the ground.

The UN estimates that there are 8,000 rebel fighters in Aleppo of which 900 belong to Fatah al-Sham, previously the al-Qaeda affiliate Jabhat al-Nusra. They can inflict heavy losses on pro-government forces in street fighting if they fight to the last, but at the end of the day they will lose unless there is a change in the military balance in Syria through one or more of the outside powers involved in the conflict intervening more forcefully in the air or on the ground. President Bashar al-Assad has made clear that he is not going to relax his grip on East Aleppo, saying that he will go on fighting “with the rebels until they leave Aleppo. They have to. There’s no other option.” It is unlikely that anybody will stop him.

The UN Special Envoy to Syria, Staffan de Mistura, has proposed that there be mass evacuation of fighters and civilians to rebel-held Idlib province. He says that he personally is “ready physically to accompany you.” The Syrian government says that it is willing to give safe passage, but this sounds better than it is because of the extreme distrust on the rebel side of any assurances from Damascus that they will be safe from the Mukhabarat secret police now and in the future. The UN says that about half the civilians in East Aleppo are ready to leave now, but this is accompanied by understandable wariness.

During the siege of the Old City of Homs two years ago, which in many ways resembles the siege of Aleppo today, I talked to a middle aged man who had evidently been on the rebel side and two of whose sons were missing. He himself was free and living with other displaced people in a school in Homs, but he could not go to Damascus to ask about the fate of his sons because he rightly suspected that he himself – the last adult male in his family still free – would be arrested on the road and detained for an indefinite period. I said that I supposed that all men of military age were at risk. He laughed hollowly and replied that “we all at risk, every single one of us.”

This fear of the Syrian security forces is a main reason why civilians and others will not want to leave. Other reasons include the sheer danger of appearing on the streets in order to go and the attitude of the rebel fighters. In most rebel-held districts in Syria and Iraq rebels of whatever stripe do not want civilians to depart because they act as human shields. In some cases, they are forcibly prevented from doing so and those that get out have to pay large bribes, as has happened in Mosul and Raqqa in recent months. An organised withdrawal from East Aleppo under the auspices of the UN may be the best option for the civilians remaining there, but the collapse of the Russian-US ceasefire shows how difficult it will be to arrange.

Are there alternative scenarios if not solutions? In Syria there usually are because there are so many players inside and outside the country, all claiming hypocritically to be acting in the interests of the Syrian people but invariably consulting their own interests first, second and third. It is difficult to see where any outside force willing to break the siege will come from. President Recep Tayyip Erdogan, normally so belligerent on behalf of the Syrian insurgents, has been surprisingly mute about the fate of Aleppo. This is probably because he is more concerned with the threat from the Syrian Kurds and on fostering goods relations with President Putin with whom he has just signed a gas deal.