Analysis: No-one should be fooled into thinking that Tehran will simply take this lying down

This is extremely unlikely and it is necessary to consider what options Iran might have. Recently, there has been much speculation, encouraged by some, but not all, elements in the Iranian power structure, that its response would be to inhibit the flow of oil through the Strait of Hormuz.

But any attempt to interfere with transit through Hormuz would in its turn provoke a response that would eventually be sufficient to keep the Strait open. This response, if transit were seriously threatened, would rapidly degenerate into a shooting war between Iran and the United States, the latter supported by many of its allies.

There are two reasons why a serious attempt by Iran to close the Strait is unlikely. Any closure would damage Iran’s ability to export the oil on which its economy is so dependent and serious attempts to close the Strait are in effect Iran’s “big guns” on the issue of whether or not the US (or Israel) would launch a military attack on Iran. The threat to close Hormuz does act as a major deterrent against a military strike. This is not necessarily because Iran could close the Strait: military confrontation with the US could have only one outcome – the oil would eventually continue to flow. But limiting oil through Hormuz would be an existential threat to the global economy and quite simply could not be allowed.

However, if Iran announced an unequivocal intention to close the Strait, backed up by credible action, the oil price would spike to high levels. This would have serious global economic consequences, especially given the current prospects for the eurozone and global economic recovery – a very powerful card that Iran is unlikely to play early.

However, Iran has other options. It could begin to aggravate upward pressures on oil prices by contributing to the growing instability in Iraq that has emerged since the US completed its troop withdrawal and the Shia ruling clique began a de facto war of attrition against the Sunnis. This could certainly cause problems with Iraqi oil exports. It could also make serious trouble for Nato in Afghanistan. There could even be a Lockerbie-type response prompted by elements from within Iran.

History is littered with failed oil embargoes ranging from Cuba, Rhodesia and South Africa to the embargo against Iraq after 1990. However, history appears to have passed by the decision-makers of the EU. An EU oil embargo would greatly strengthen the Ahmadinejad regime by putting the population solidly behind the current regime.

• Professor Paul Stevens is senior research rellow in energy, environment and resource governance at Chatham House