"Britain doesn't sell weapons". The arms dealers aren't civil dpservants, and the businesses they run aren't in public hands, so thats true enough. But the dealers are British often enough, and the goods they supply are often enough made in Britain. The essential truth is that this is an international trade, "globalised" to use current terminology. Bans and sanctions are evaded with the greatest of ease.

But what has any of this got to do with the point at issue? - how to prevent the war in Syria getting worse and wider, and is there anything that can be done to end it.