In 2011, the revolution in Libya rocked world energy markets. Last year, the threat was sanctions on Iran. This year, is it insecurity in the great ungoverned Saharan spaces between Mali, Algeria and Libya?
Last week, a group of militants attacked the Ain Amenas gas facility in eastern Algeria, run by BP, Statoil and the state oil firm Sonatrach, in apparent retaliation for France's intervention in Mali. Without consultation, the Algerian military struck to end the siege, with reports of at least 50 hostages killed.
Oil companies have long experience of operating under troubled conditions in Algeria. Most of the country's fields are in the interior, south of the Atlas Mountains, heavily militarised and sparsely-peopled. Even during the vicious 1991-2002 civil war, in which some 100,000 people were killed, there were almost no attacks on oil installations.
The Ain Amenas attack thus comes as a shock. Firstly, it is the first successful assault on a defended petroleum facility in Algeria - the militants may have planned to destroy it. Secondly, it is 1,000 kilometres from the Mali border, from where the obvious threat seemed to emanate. Thirdly, it casts doubt on the competence, even complicity, of Algeria's security forces. And fourthly, it makes us wonder where else in the Sahara may be vulnerable.
Oil and gas provide 95 per cent of Algeria's export earnings, and so underpin its social model - based, to an even greater extent than in most petro-states, on subsidies and state employment. The Algerians' ruthless response is not surprising.
Algeria is the third-largest gas supplier to Europe, helping to diversify away from Russia, and Ain Amenas alone produced almost a fifth of exports. A lone attack may not make too much difference to the country's investment image, anyway already tarnished by harsh tax terms.
Sonatrach can continue operations even if many foreign staff are withdrawn, deterred by the military's apparent disregard for hostages' lives. After this shock, Algeria's pervasive security state will no doubt reinforce the protection of its lifeline. The major energy security focus therefore shifts to weaker neighbours.
The French intervention in Mali was not driven by oil - it has none (at least, none has yet been found). However, all the other Saharan countries possess oil and gas in some quantity. Next-door Niger, though so far only a miniscule oil producer, is the world's fourth largest uranium miner, a major part of supply to France's power stations. ExxonMobil operates heavily-fortified fields in Chad. Oil exports from Sudan and South Sudan have been seriously disrupted since the countries' 2011 separation.
The heavyweights, of course, are Algeria and Libya. Between them, they supply about 3.7 million barrels per day, 4 per cent of the world's total. Libya's facilities escaped the 2011 overthrow of Muammar Qaddafi surprisingly unscathed. But the Ain Amenas attackers apparently crossed over porous borders from nearby western Libya - an area which yields about a quarter of the country's production. The Libyans rushed to strengthen their Petroleum Facility Guard after the attack, but this unit seems still unready.
Experience from terrorist and insurgent attacks on energy infrastructure in Yemen, Iraq, Pakistan, Saudi Arabia, Egypt's Sinai, Nigeria, Colombia and elsewhere suggests that well-defended facilities are a hard target. In this respect, last week's attack is an aberration. Trickier to protect are pipelines snaking across hundreds of kilometres of deserts and mountains.
Most vulnerable of all are oilfield workers - who can be intimidated, kidnapped or killed, as in last week's tragedy. In the vast open deserts, they are suddenly on the front line. Ain Amenas is not the herald of a new energy crisis - but it should catalyse oil companies, regional states and international partners to build a comprehensive Saharan security strategy, that does not rely on guns alone.
Robin Mills is Head of Consulting at Manaar Energy, and author of The Myth of the Oil Crisis and Capturing Carbon.