So how can wars be stopped? Look at the disease again. What causes the deaths and injury?
Explosives, mainly, and for the sake of simplicity, let's look at explosives. Basically, we are taught by the news that there are good explosives, bad explosives and silly explosives. Good explosives are fired by "our side", bad explosives are fired by "their side" and silly explosives are used in wars in which we have no interest.
So the disease model is of a body which is being infected with bad bacteria, and we send good bacteria to fight the bad bacteria, and an abscess forms. When the war has run its course, as all wars do, the abscess is sealed off, but resentments in the group memory persist.
Humanity has about 44 such abscesses in its body at the moment.
Now it is clear that this "good bacteria/bad bacteria" model, with the good sent to neutralise the bad, is ridiculous and worthless. Clearly, the dichotomy is false. All killing is bad. All wars have mixed values, none more so than Syria, which is a confused mess of competing alliances and oppositions and interests.
It would be much better to do away with bacteria in the first place. In other words, to do away with the explosives that magnify the power of war.
It is true that there were wars before there were explosives, and that the main instrument of the Hutu-Tutsi genocide of 1994 was the machete, but it is equally true that explosives greatly magnify the corpse-productivity of the individual soldier. This is why our soldiers are equipped with machine guns rather than swords.
Now there are legal explosives and illegal explosives. Let's start with the illegal ones. The beauty of it is that with the exception of acetone based species, explosives can be detected at range by trained sniffer dogs, bees, and other approaches.
Sniffer dogs are inexpensive and an established technology. They can be deployed extensively while other approaches are developed. They can be deployed at borders, and even driven around the countryside with their noses to the wind. If they react, they can be moved upwind until the source of the odour is located, be it an arms cache or ammunition factory.
The beauty of concentrating on ammunition and explosives rather than on armaments is that a dog cannot distinguish between a lorry containing arms and one containing sewing machines, but it can point to a lorry containing explosives.
Therefore we have the means and ability greatly to reduce the amount of ammunition on the planet. We can even generate electricity while disposing of ammunition, if bullets are fired at a robust Pelton wheel attached to a generator.
So why not? The objections will come from arms companies and their bought politicians. This is where a world wide popular movement is needed to motivate a majority of reasonably non-corrupt politicians to begin to work together to reduce the amount of illicit ammunition on the world market.
This is already Green Party policy - PD 434 here.
Of course there are other measures available. The United Nations needs to build on and develop the Arms Trade Treaty, especially the parts relating to ammunition.
So we do not have to sit back and watch Aleppo suffering silently. We can begin to build the political will to stop the Aleppos of the future.