Whilst all the attention has been focused on Turkey, there has been a possibly decisive military development in Syria. It seems the Syrian army has succeeded in reaching the Castello road thereby cutting off the last big supply route from Turkey to the rebels in Aleppo.
That means that the rebels in Aleppo are now besieged.
Here it is important to make some qualifications. This is not the sort of siege that used to happen in the Middle Ages when an army would surround a town or castle whose garrison and population would then be completely cut off from the outside world. The Syrian army does not have the manpower to besiege the rebels in Aleppo in that way. It cannot control every inch of the territory around Aleppo and there are still plenty of ways for rebel fighters both to enter and exit the area of the city they control.
Also, as I said previously, the rebels have undoubtedly stocked up substantial supplies within the city and there are manufacturing plants and workshops within the city they can use to make ammunition and light weapons (including mortars and possibly even AK47 copies). Nor will the Syrian authorities prevent food, water and gasoline from entering the areas of Aleppo the rebels control, and nor will they cut off the electricity supply to those areas.
What the closure of the Castello road will however do is prevent the rebels resupplying from Turkey with heavy weapons – including sophisticated weapons like TOW anti tank missiles – and sending large reinforcements to Aleppo. Over time in what is a battle of attrition that will steadily reduce their effectiveness as they suffer increasing losses they cannot replace. In the end that will be decisive. However that does not mean the fighting in Aleppo will soon be over. On the contrary the fighting in Aleppo looks set to continue for months.
Given the importance of the Castello road the rebels will probably redouble their efforts to reopen it. All their attempts to prevent the Syrian army reaching it have however failed, and it would now take a dramatic change in the balance of forces in and around Aleppo for that to reverse. That would almost certainly require US intervention.
I once compared the battle for Aleppo to the battle of Stalingrad. Indeed the parallels are very strong. The battle of Aleppo began in the summer of 2012 with an attempt by the rebels to storm the city – much as the Wehrmacht tried to storm Stalingrad in the summer of 1942. When that failed the fighting in Aleppo settled into a grinding siege, as the rebels slowly encircled the city and sought to enlarge incrementally the area of the city they controlled. That too repeats – though obviously over a much longer period – the pattern in Stalingrad in the autumn and early winter of 1942. There has now been a Syrian army counter attack which has left the rebels – the former besiegers – in turn encircled and besieged. That too of course repeats what happened in Stalingrad during the winter of 1942-1943. Moreover for the reasons I set out in my previous article, the battle of Aleppo is likely to be at least as decisive in deciding the future course of the Syrian war as the battle of Stalingrad was in deciding the course of the Second World War.