Conspiracy theorists have long insisted that modern wars revolve around oil. Now research suggests hydrocarbons play an even bigger role in conflicts than they had suspected.

According to academics from the Universities of Portsmouth, Warwick and Essex, foreign intervention in a civil war is 100 times more likely when the afflicted country has high oil reserves than if it has none. The research is the first to confirm the role of oil as a dominant motivating factor in conflict, suggesting hydrocarbons were a major reason for the military intervention in Libya, by a coalition which included the UK, and the current US campaign against Isis in northern Iraq.

It suggests we are set for a period of low intervention because the falling oil price makes it a less valuable asset to protect. “We found clear evidence that countries with potential for oil production are more likely to be targeted by foreign intervention if civil wars erupt,” said one of the report authors, Dr Petros Sekeris, of the University of Portsmouth. “Military intervention is expensive and risky. No country joins another country’s civil war without balancing the cost against their own strategic interests.”

Iraqi forces recaptured the country's largest oil refinery, in Baiji, from Isis in November (Getty) (Getty Images)

The report’s starkest finding is that a third party is 100 times more likely to intervene when the country at war is a big producer and exporter of oil than when it has no reserves. “After a rigorous and systematic analysis, we found that the role of economic incentives emerges as a key factor in intervention,” said co-author Dr Vincenzo Bove, of the University of Warwick. “Before the Isis forces approached the oil-rich Kurdish north of Iraq, Isis was barely mentioned in the news. But once Isis got near oil fields, the siege of Kobani in Syria became a headline and the US sent drones to strike Isis targets,” he added.

The study, published in the Journal of Conflict Resolution, analysed 69 civil wars between 1945 and 1999, but did not examine foreign invasions. It noted that civil wars have made up more than 90 per cent of all armed conflicts since the Second World War and that two-thirds of these have seen a third-party intervention.

Biggest oil producers (IEA figures) Show all 10 1 /10 Biggest oil producers (IEA figures) Biggest oil producers (IEA figures) 1. USA (12.35 million barrels per day) Getty Biggest oil producers (IEA figures) 2. Russia (10.95 million barrels per day) Getty Biggest oil producers (IEA figures) 3. Saudi Arabia (9.51 million barrels per day) Getty Biggest oil producers (IEA figures) 4. (4.21 million barrels per day) Rex Biggest oil producers (IEA figures) 5. China (4.13 million barrels per day) Getty Biggest oil producers (IEA figures) 6. Iraq (3.38 million barrels per day) Getty Biggest oil producers (IEA figures) 7. Iran (2.76 million barrels per day) Getty Biggest oil producers (IEA figures) 8. UAE (2.71 million barrels per day) Getty Biggest oil producers (IEA figures) 9. Kuwait (2.66 million barrels per day) Getty Biggest oil producers (IEA figures) 10. Mexico (2.64 million barrels per day) Getty

The researchers drew their conclusions after modelling the decision-making process of the third-parties’ interventions. This assessed a wide range of factors such as their military power and the strength of the rebel army, as well as their demand for oil and the level of supplies in the target country. It found that the decision to intervene was dominated by the third-party’s need for oil, far more than historical, geographic or ethnic ties.

The US maintains troops in Persian Gulf oil producers and has a history of supporting conservative autocratic states in spite of the emphasis on democratic reform elsewhere, the report says. However, the recent surge in US oil production suggests the country will be intervening less in the future – with China potentially taking up the role as lead intervener, the report suggests.

Well defended: Britain’s military interventions

When the UK intervened

Britain intervened in the Nigerian Civil War, also known as the Biafran War, between 1967 and 1970. During this period the UK was one of the biggest importers of oil in the world, with North Sea oil production only starting in 1975. BP’s presence in the oil-rich eastern region of the country meant stability in the area was of critical importance.

Biafran soldiers during Nigeria’s civil war in 1967 (Getty) (Getty Images)

The invasion of Iraq in 2003, led by the US and the UK, wasn’t covered in the research because it wasn’t a civil war. However, the report notes previous claims that a thirst for oil was “the alleged ‘true’ motivation of the US invasion of Iraq”.

David Cameron was instrumental in setting up the coalition that intervened in Muammar Gaddafi’s Libya in 2011, a country with sizeable oil reserves.

When the UK did not intervene

Britain watched on as Sierra Leone’s Revolutionary United Front, with support from Charles Taylor’s National Patriotic Front of Liberia, attempted to overthrow Joseph Momoh’s government. The resulting civil war lasted 11 years (1991 to 2002) and enveloped the country, leaving more than 50,000 dead.

The UK also opted not to intervene in the Rhodesian Bush War between 1964 and 1979 – a three-way battle between the Rhodesian government, the military wing of Robert Mugabe’s Zimbabwe African National Union and the Zimbabwe People’s Revolutionary Army.