TWO out of three African countries have substantially increased military spending over the past decade; the continent as a whole raised military expenditure by 65% during that period, after it had stagnated for the previous 15 years. Military spending grew faster in Africa last year than in other parts of the world, according to the Stockholm International Peace Research Institute. The reasons for the splurge vary. High commodity prices over the past decade (they are now falling) have filled the coffers of many: some leaders have been tempted to buy expensive arms to gain prestige. Other are suspected of inflating deals to siphon off money for themselves. But some spending is prompted by genuine security threats. The Sahel and parts of east Africa face a range of jihadists. Coastal states have seen piracy soar, most recently in the west. Offshore discoveries of oil and gas have increased the need for maritime security. More traditional threats, internal as well as external, persist in countries such as South Sudan, where the government is fighting rebels while also facing a hostile northern neighbour. Industrial ambition also plays a part: a number of countries hope to foster defence manufacturing at home.