" let Syria do what it wants within its own borders" Is that; By all means?
Perhaps Armies don't kill, just as guns don't kill. So perhaps all is well and good that major arms exporters share your view David, that the middle east is a ready-made market for 'our' armaments. They probably need lots, so we shall sell them lots, and if/when they begin to use up their stockpiles , again, all well and good.
Major arms industry corporations by nation
https://en.wikipedia.org/wiki/Major_arms_industry_corporations_by_nation
No Syria, Afghanistan or Iraq on the list.
Arms exporters, again no Syria, Afghanistan or Iraq...
https://en.wikipedia.org/wiki/Arms_industry#World.27s_largest_arms_exporters