The idea of using oil as a weapon calls to mind the Arab oil embargo of October 1973, when prices quadrupled overnight and the US, Europe and Japan, then the biggest energy consumers, saw long queues at petrol stations. The industrialised world was thrown into turmoil by the turn of the spigot. In response it created the International Energy Agency to protect security of supply and thus make it harder for the global economy to be held to ransom by the actions of a few producers.

Yet in the history of oil warfare, consuming nations have generally been the aggressors rather than the victims. As A.F. Alhajji, a US-based energy economist has pointed out, the consumers rather than the producers have more often used the oil embargo as a tool of diplomacy or warfare over the last 75 years. Washington alone has “historically imposed a greater number of oil embargoes than any other nation”. Targets have included Japan before the second world war; the Soviet Union in the 1960s; as well as South Africa, Burma, Serbia, Haiti, Libya, Iraq, Iran, and Sudan in the last two decades.

Indeed the tempo is increasing. Europe has imposed embargoes this year on Libya and Syria to press the regimes. Brussels is mulling an embargo on Iran to stop Tehran’s nuclear programme. The US itself is considering fresh sanctions against Iran’s central bank. De facto, that could mean a universal oil embargo, since China and India – two allies of Iran – would face colossal difficulties to pay for the oil they buy from Tehran.