In January 2012, Iran threatened to block the Strait of Hormuz, a key global oil passageway through which 17 million barrels of oil passed every day in 2011. The threat was prompted by sanctions, including an oil embargo imposed on Iran by the US and the 27-nation EU over its contentious nuclear programme.
The West insists the programme is aimed at producing atomic weapons, but Iran vehemently denies this charge, claiming it is designed to generate civilian electricity and produce medical radioisotopes needed to treat cancer sufferers.
The US and the UK responded strongly to Iran's threat to block one of the world's most crucial oil conduits, with senior Obama administration officials saying that Iran would cross a "red line" if it made good on its threats. General Martin E Dempsey went as far as to state the US would "take action and reopen the strait", a feat that could only be accomplished by military means. UK Defence Secretary Philip Hammond warned in a similar vein that any blockade of the Strait of Hormuz would be "illegal and unsuccessful".
Global oil threat
A strategically crucial waterway connecting the Persian Gulf to the Gulf of Oman, the Strait of Hormuz sees about a fifth of the world's daily oil trade. Analysts warned in January 2012 that the price of Brent crude could temporarily jump to as high as $210 if it were closed, significantly impacting the global economy.
According to Dr Lee Willett, senior research fellow in the Maritime Studies programme at the Royal United Services Institute (RUSI), the region is so important to global powers that they will do whatever it takes to ensure the Strait of Hormuz stays open.
"This is one area that the UK will not compromise on," he says. "It will gap [drop] other commitments elsewhere rather than compromise its strategic position in the Persian Gulf, which is simply too important to national interests."
But does Iran really have either the military capacity or the desire to carry through on its threat? For David Roberts, deputy director of RUSI Qatar, it's possible, but not for long.
"It's unrealistic for anyone to say 'Yes, Iran can definitely close it for an indefinite period of time' or 'No, it can't," he says. "Iran's strength lies in its asymmetric capacity, and, by definition, it's quite tricky to work out exactly what that is - what weapons it would use, how exactly it would use them and when they would use them. But, given that Iran would have first movement advantage, it seems more than likely that it could 'block the strait'."
Willett agrees. "Iran has fast-attack craft, surface-to-surface cruise missiles and submarines," he explains. "It also has a new submarine base at Jask, right at the mouth of the strait, which gives it more leverage and the potential to deny access to the strait at an earlier phase. One single submarine can have a major strategic impact on how a conflict unfolds."
The more important question is whether the Iranians have any desire to block the strait, and on that point, Willett is sceptical. "Firstly, Iran relies on it economically, as much as anybody else does, and secondly, the region is so important to other nations that it would act with a significant military response," he explains.
"The potential retaliation from the US is absolutely devastating," Roberts adds. "It's conceivable that Iran would lose any and all its waterborne vessels of the military variety quickly. Although, domestically, it will get a huge surge of rally around the flag, the basic ramifications could be terrible for Iran. It knows perfectly well that it can't begin to take on the US."
It's not only the US that Iran would have to deal with; the British Navy deployed the £1bn HMS Daring, a Type 45 destroyer, to the Persian Gulf in January 2012 in response, some claim, to the imminent threat from Iran. Not only does the warship have the technology to shoot down any missile in Iran's armoury, it also carries the world's most sophisticated naval radar, which is capable of tracking multiple incoming threats. Yet for Roberts, the deployment of this ship was not as significant as many news reports have implied. "Because of the Doha International Maritime Defence Exhibition and Conference [held in March 2012], there are a lot of port visits around this time of year," he says. "The Royal Navy committed to sending a least one or two ships and they've known about this for months; however, it is a possibility that the choice of ship changed on the back of what the Iranians said."
Willett agrees that one shouldn't read too much into the deployment of HMS Daring: "The Royal Navy is in the process of bringing into service the Type 45 destroyer, a new class of ship, and the simple fact of the matter is that the first few of this new class are available for deployment now and are going to take the next task in hand," he explains. "It's a coincidence rather than any sort of strategic plan for the UK to increase pressure and presence."
The deployment of the UK's mine-countermeasure ships is a far more significant move, according to Willett. "The UK has state-of-the-art mine-countermeasure capabilities that few other nations, including the US, have, and our primary mine capability is now forward-deployed in Bahrain on behalf of the coalition interests."
Despite its largely routine nature, perhaps the increased naval presence in the region has had an effect on Iran, as talks that took place in Istanbul in April 2012 between Iran, the US, Russia, China, Germany, France and the UK led to the most productive negotiations on the nuclear programme in 15 months, with delegates praising "the constructive dialogue and Iran's positive attitude" according to the Guardian. A source at the talks told the newspaper that there had been a string of signals from Tehran that it would be prepared to limit its enrichment of uranium in return for a relaxation of sanctions.
For Roberts, this development is not surprising. "I fundamentally believe that Iran really doesn't want this continuing kind of cold war," he says. "Yes, it serves some political ends domestically, but more generally, I think Iran is a perfectly rational actor and perfectly rational actors don't really want conflict. It wants to de-escalate things, but, like the US, it has to do it in a way that saves face."
Looking to the future, there is one issue that could put a whole different spin on the situation: the direction of Iran's nuclear programme.
"There is some public evidence that suggests that some of the things Iran is doing are taking its programme in one direction and one direction only, a weapons programme, and that's the strategic unknown in all of this," Willett explains. "A nuclear power sitting astride the Strait of Hormuz is a different matter; whether it would make Iran more aggressive or more cooperative, no one can tell, but in terms of making a military threat to close the Strait of Hormuz, the message is different if you're a nuclear power."
Hypotheticals aside, the situation seems to be progressing in a positive direction and, for Roberts, there will be little change in the naval presence in the region over 2012. "Barring some obvious escalation from the Iranian side, not necessarily caused by them, I don't see any imminent changes," he says.
This article was first published in our sister publication Defence & Security Systems International.