Reprehensible as it is, the arms trade is an exercise of purgatorial ethics pursued by all states keen on having a market for the merchants of death: from the perspective of countries and those who represent them, it’s a matter of cold business and hot transactions. The principles (how the arms will be used, how many innocents will be butchered) can go and sod themselves. No other figure in modern times has been as candid about this fact than US President Donald Trump. When confronted with the unsettling…