To discuss international arms trading in isolation totally obscures the reality. Politics, economics, strategic considerations are an integral part of the mix, and account for the complexity of the traffic.
A middle eastern alliance of Saudi and other major middle eastern oil and gas producers with China and Russia would have major ramifications for the western world. Arms sales are a way of preserving the status quo, so if they want the 2017 version of battlefield toys from the west they will get them-despite all the squawking of the pacifists.
It is a very joined up world and the resulting instability from pulling rhe plug here and there is very hard to predict.
    You may feel very smug stopping the international arms trade, but that is very little consolation as you starve to death ,dressed in rags, sitting in the dark with no transport.