With oil prices already stretched to record highs, a terrorist attack targeting vital oil installations would have immediate global consequences, experts say.
Wells, pipelines, refineries and tankers have all been targeted in recent years by al Qaeda-linked groups, or by local armed militants such as in the Niger Delta - and many remain poorly protected against potential attacks.
On February 24, Saudi security forces foiled an attack on oil installations in Abqaiq, which account for 70 percent of the country's output, and 10 percent of the world's, sending jitters through the oil sector.
According to Gal Luft, head of the US-based Institute for the Analysis of Global Security (IAGS), the attack - had it succeeded - would have cut four to six million barrels per day out of an already tight oil market.
"It would have exceeded all of the oil taken off the market by the OPEC (Organisation of Petroleum Exporting Countries) during the 1973 Arab oil embargo," he said.
For Michael Klare, head of the Peace and World Security programme at the University of Massachusetts, author of the study "Resource Wars", oil markets are vulnerable because of a serious lack of spare capacity.
"Without Iraq, there is very little spare oil in the world: every bit of oil is in use," Klare said. "Even a small interruption in the supply of oil would push prices up."
"That's why the American military is increasingly being converted into a global oil-protection service."
In Nigeria, for example, local militant attacks on oil installations have removed 600,000 barrels per day from the global oil market, according to Roger Diwan, an analyst with the New York-based PFC Energy. "That weighs on world prices," he said.
Whether to press local demands or a world-wide political agenda, many armed groups have understood that oil sites were an Achilles' Heel for the West.
In a video broadcast in December, al Qaeda number two Ayman Zawahiri called on "mujahedeen to concentrate (their) attacks on oil stolen from Muslims, from which most revenues go to the enemies of Islam."
On an Islamist website, translated by the IAGS, a militant calls on "our brothers in the battlefields to direct some of their great efforts towards the oil wells and the pipelines."
"The killing of 10 American soldiers is nothing compared to the impact of the rise in oil prices on America and the disruption that it causes in the international economy," he said.
Earlier this year, the US institute SITE, which monitors Islamic extremist websites, said it had discovered a password-protected forum listing 12 pages of potential targets for attacks.
They included oil installations in Iraq, Afghanistan and Turkmenistan, as well as the Trans-Alaska oil pipeline - complete with maps and diagrams showing where to strike for maximum impact.
Around 40 percent of world production transits via oil pipelines, many above ground, and crossing politically troubled regions.
With 6,400 kilometres (3,820 miles) of pipelines in Iraq, and 16,000 kilometres in Saudi Arabia, such installations are impossible to protect day and night.
Diwan stressed however that pipelines remained minor strategic targets: "An attack on a pipeline is not too serious: just a piece of tubing to replace. With a helicopter it can be done within a day."