Iranian President Hassan Rouhani this month declared that Iran would close the Strait of Hormuz if the US blocked Tehran's export of oil.
"If someday, the United States decides to block Iran's oil [exports], no oil will be exported from the Persian Gulf," Iranian state television quoted him saying.
Tehran has made similar declarations about closing the narrow Strait of Hormuz - where one-fifth of the world's oil supply today transits through from the Gulf into the Indian Ocean - over the past 40 years, whenever it has felt threatened.
Fears of the strait being blocked go back even further than that.
When Britain withdrew its military forces from the Gulf back in December 1971, its historic pullback from east of the Suez Canal, Iran under the last shah, Mohammad Reza Pahlavi, rushed to fill the power vacuum and become the predominant force there.
Tehran seized Abu Musa and the Great and Lesser Tunbs islands, ownership of which has been disputed with the United Arab Emirates (UAE). The islands are of immense strategic importance since they sit at the entrance to the Gulf from the strait.
Iran took hold of the islands in an agreement with the Sharjah Emirate a mere two days before the UAE was officially established. Under the agreement, Sharjah could maintain a police station on the islands while Iran established a troop presence there.
The British announced their phased withdrawal in 1968 and questions about how the region would be secured were raised in the following years. London conceded from the get-go that it could hardly leave a perfectly stable region in its wake.
"If British arms were to stay until everything were sorted out, they would stay forever," said one 1970 analysis in The Guardian. "The attraction of going now is that nobody is shooting yet, as they were before we left Aden."
| Whoever holds the reefs of Hormuz can stop the wheels of all the world |
Upon Britain's complete withdrawal in December 1971 one article in the Chicago Daily News aptly summed up the strategic significance of the Straits of Hormuz, describing it as "the doorway to the oil riches of the Persian Gulf, a turnstile of the sea strategically as valuable as Panama, the Dardanelles, Suez or Singapore".
"Whoever holds the reefs of Hormuz can stop the wheels of all the world, except those of Russia and the two Americas," the article added, noting that roughly one tanker passed through the strait every 15 minutes.
The shah had grand plans for ensuring the Gulf would be under Iranian control for many decades to come. Just as the British were packing up and leaving he began building a new naval base in Bandar Abbas, which one estimate at the time said would "one day be as important in overseeing the oil traffic of the world as once was British Aden, on the opposite side of Arabia".
"For us, the control of the Gulf and the Straits of Hormuz is not a problem, because with 1,000 kilometres of coastline and 10 naval and air bases, we can always close the strait," Pahlavi said in 1972.
In 1973, Tehran asked Oman to jointly inspect ships crossing through the strait. Around the same time, the shah also expressed his "displeasure" to Soviet Premier Alexi Kosygin over the presence of Soviet ships in the Gulf, indicating that no foreign force should be permitted access without his approval.
Iraq used the shah's takeover of Abu Musa as justification both for breaking relations and for expelling 60,000 Iranians living in Iraq - some of whom had lived there for an entire generation.
One of the shah's justifications for taking the islands, aside from seeking some small compensation for relinquishing Iran's claims to Bahrain, was the comparative weakness of the Gulf Arab states at that time, which he argued might have lost the islands to hostile forces which could then threaten shipping in the strait.
"If those islands fell into the wrong hands, it could pose a terrible danger," he warned.
One hostile force the shah feared somehow taking Abu Musa or otherwise threatening oil shipping transiting the strait were Marxist insurgents fighting in Oman's Dhofar region. Iran intervened in that war, at the invitation of Omani leader Sultan Qaboos, by sending in helicopters and troops who helped Muscat crush the insurgency.
"In fact, the Iranian reaction to Sultan Qaboos' request was as powerful as if the Dhofari rebels had occupied the whole of southern Iran," noted one historical account of that war.
"Suppose Oman fell into the hands of the wrong people who could control the Straits of Hormuz with long-range guns or who would sink a 500,000-ton tanker, which would pollute the Gulf forever?" the Shah remarked in 1974 when justifying Iran's intervention.
In another interview with The Los Angeles Times, also in 1974, Pahlavi portrayed his intervention as an endeavour that benefitted the entire region, arguing that all the states along the Gulf would be threatened were Hormuz to have fallen "into the hands of people who are opposed to our regimes".
Describing the strait as Iran's "jugular vein", the shah also said Iran would not accept the presence of "any forces of subversion, destruction, chaos and murder which might come close to the entrance to the Gulf".
His longest-serving prime minister, Amir Abbas Hoveyda, also tried to convey to outside powers the global importance of the Strait of Hormuz. "It is our jugular vein, and yours too," he once remarked upon noting that 60 percent of Europe's and 90 percent of Japan's oil passed through that key area.
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Omani insurgents reportedly tried twice during the 1970s to hijack and sink supertankers passing through the strait.
Throughout the 1970s, the shah expanded his naval forces with frigates and hovercraft from Britain, becoming the largest and most powerful naval power in the Gulf. Iran even possessed the largest hovercraft fleet in the world at that time. These speedy crafts were put to use as part of his expanding naval capability to protect the narrow strait, which is roughly 21 nautical miles, or about 39 kilometres, wide at its narrowest point.
Once asked by a British reporter why he needed such strong armed forces the shah pointed to Iran's "geographical location".
"Have you ever thought about the Strait of Hormuz, that is the entrance of the Persian Gulf?" he added. "This is our lifeline, and this is for us a question of life and death. If this is ever closed, we're dead, we're finished."
In that same interview he also blithely dismissed the insurgents in Oman as "savages in the mountains, living like goats and acting like terrorists".
The Iranian Revolution, which saw the shah flee the country in January 1979 and American diplomats taken hostage the following November, plunged Iran into chaos and led to concerns that the new regime, led by Ayatollah Ruhollah Khomeini, would threaten the strait.
"Every oil tanker leaving the Gulf must sail through the Straits of Hormuz - right under the muzzles of Iranian guns," wrote noted columnist Jack Anderson early in the revolution. "It would be a disaster if Iran fell into hostile hands. Yet today, Iran is in turmoil."
Nevertheless, the US did not worry too much about the Strait of Hormuz being closed off, thanks in large part to Oman.
"Because the Omani army and air force have been trained by the British, and a number of British officers and non-commissioned officers remain in the forces, American officials consider the strait secure on its all-important southern shore," reported The New York Times in December 1979.
After Saddam Hussein's Iraq invaded Iran in 1980, instigating the brutal eight-year Iran-Iraq war, Tehran threatened to close off the strait on several occasions throughout the rest of the 1980s.
Early in the war, Saddam also said he would seize Abu Musa from Iran, one of his pretexts for attacking the country.
"One of the few things that Iran's Ayatollah Ruhollah Khomeini and the late Shah Mohammad Reza Pahlavi agreed on was that those three islands belong to Iran, which first claimed them in 1904," noted The Baltimore Sun shortly after the Iraqi invasion. "And one thing which all the Arab states agree upon is that the three islands are Arab. Iraq has set as one of its objectives their return to Arab control."
Iraq reportedly even sent, or at the very least contemplated sending, forces to states in the southern Gulf region for an operation to seize the three islands from Iran. This was possibly part of a broader bid to "implicate" the Arab Gulf states in the war so Iraq could become their "protector", making them more dependent on Baghdad.
Initial reports of the deployment shortly after the war started, "edged the world oil industry slightly more to the point of panic".
Writing in The Guardian in September 30, 1980, Energy Correspondent John Andrews noted that while "low demand and high oil stockpiles" instilled some confidence, "the danger remained that if the conflict moves from its Iraq-Iran axis to embrace the mouth of the Gulf at the Strait of Hormuz, the world will suddenly lose a quarter of its total production".
Two weeks later, The Los Angeles Times noted that the two "chief sheikdoms of the United Arab Emirates, Abu Dhabi and Dubai, have been lukewarm at best to the call by Baghdad for Iran to return the three islands".
Ras al-Khaimah Emirate, the "former titular owner" of the Tunbs, on the other hand, "backed Iraqi demands for their return".
TheTimes pointed out that Ras al-Khaimah had "the least to lose in the way of oil installations or ports in the event of Iranian air force retaliation".
| The Gulf Arabs will not allow Iraq to use their soil for an attack on the islands, while in return Iran will not attack navigation in the Gulf |
Also, in mid-October 1980, a large fleet of American, British and French warships assembled in the Indian Ocean to ensure the commercial shipping lane through the Strait of Hormuz remained open and unmolested by the fledgeling war. That presence served, among other things, "as a warning to Iraq" against attacking Abu Musa and the Tunbs in any planned operation "staged from nearby Arab nations such as the United Arab Emirates or Saudi Arabia".
Official Western sources cited in press reports at the time "raised the possibility of at least a tacit understanding - and perhaps more - that the Gulf Arabs will not allow Iraq to use their soil for an attack on the islands, while in return Iran will not attack navigation in the Gulf".
The US also conveyed both to Baghdad, through King Hussein in Jordan, and its Gulf allies, its opposition to the purported Iraqi plan, which is likely to be at least one major reason why it never materialised.
In October 1983, Tehran warned it would block oil exports from the Gulf if Iraq used Super-Etendard bombers it had leased from France against Iranian installations in the area. Analysts at the time varied in their estimates over whether Iran could actually do this.
One analyst suggested Iran could close the straits, provided no third country intervened, since, even with Super-Etendards, Iraq could do little to stop Iran controlling the Gulf because it lacked a long-range reconnaissance capability or a navy that could present a serious challenge to Iran's.
The Saudis also said they would respond to any Iranian attempt to blockade the strait. By the end of 1983, Riyadh reportedly began stockpiling oil outside the Gulf in case such a blockade transpired.
October 1983, incidentally, marked the 10th anniversary of the October 1973 oil crisis which severely harmed the oil-dependent industrialised economies of the West. Iranian threats around that time to "turn the Strait of Hormuz into a quagmire for the West's imperialist objectives" led some to briefly fear that a third oil crisis, the second being in 1979, could soon transpire.
However, Iran would unlikely have shut the strait since it needed it to export its own oil, its only major source of income to fund its enormously expensive war effort. So long as it could export oil and generate revenues it would not shut the strait and bankrupt itself in the process.
"Iranian statements have made clear that Iran will only close the strait if Iraqi attacks have already stopped Iranian oil exports and left Tehran with nothing to lose," reported Reuters at the time.
The report noted that Iran could export 1.8 million barrels of oil per day, plenty to pay for the war and its own domestic economic needs. Furthermore, Iran's naval supremacy permitted it to export goods from Bandar Abbas. By stark contrast, Iraq's only major port, in Basra, was closed off since it launched the war back in 1980.
| There's no way we could allow that channel to be closed |
In February 1984, Iran once again threatened to close the strait if the US took any action against it.
"We have always said from the start and will continue to say that so long as our ships can pass through the Hormuz Strait we will not do anything to anybody," said Ali Khamenei, who was the president of Iran at the time.
"But should US fleets and their supporters wish to do anything in the Hormuz Strait, their fate would decisively be worse than their fate in Lebanon… We would destroy all US interests in the Persian Gulf," he added, alluding to the bombing of a US Marines barracks in Beirut the year before, an attack which killed at least 241 American servicemen who were there as peacekeepers.
"There's no way we could allow that channel to be closed," US President Ronald Reagan told a press conference that very same month.
Khamenei once again warned that Iran could close the strait on the fifth anniversary of the war's start, September 1985. Shortly after Saddam Hussein claimed Iraq could destroy Iranian targets in the Gulf, as well as deep inside the country, Khamenei declared: "If Iraqi attacks cut our [oil] exports, we shall close the Strait of Hormuz with all our might to all exporting countries in the region."
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The other Gulf countries, many of which financially supported Iraq's war effort out of fear of Iran exporting its revolution across the region, were wary of Iranian domination of the Gulf as well as the strait, where it frequently searched ships passing through.
"The strait is not owned by Iran," declared Kuwaiti Foreign Minister Sheikh Sabah al-Ahmed al-Sabah in September 1985. "It belongs to all the world… It is not in world interests to interfere with shipping in international waters."
Iran justified such actions as necessary to prevent Iraq from importing anything of "strategic value".
When Iran began targeting tankers, the United States and the United Kingdom intervened directly. The US reflagged Kuwaiti tankers and escorted them through the Gulf and the Hormuz Strait.
The Americans first clashed with Iran's Islamic Revolutionary Guard Corps (IRGC) in the Gulf on October 19, 1987, when the US destroyed oil platforms used by the group in retaliation over an Iranian attack on one of the reflagged Kuwaiti tankers three days earlier. After a US warship struck an Iranian mine, the Americans again retaliated and - in a one-day operation on April 18, 1988 - destroyed an Iranian frigate and crippled another, killing dozens of Iranian servicemen in the process.
On July 3, 1988, the missile destroyer USSVincennes infamously shot down an Iranian civilian airliner - killing 290 civilians - during an engagement against IRGC boats. Washington claimed the incident was a case of mistaken identity. A few weeks later the Iran-Iraq War came to an end after Tehran accepted a UN ceasefire agreement.
Throughout the 1970s and 1980s, speculation abounded that a single supertanker sinking in the strait could completely block it and cripple Western economies in the process. Political commentator George F Will challenged this notion in a 1989 column, written in the same year a Saudi tanker caught fire in the strait.
"It has been said that if the Strait of Hormuz was closed, the lights would go out. But that strait is hard to close and harder still to keep closed," Will wrote. "Anyway, last year, one day, five tankers were burning in the Gulf and the price of oil barely moved. Markets know the oil will flow."
Iran remained neutral in the 1991 Gulf War when an enormous US-led military coalition decimated the Iraqi armed forces to punish Saddam Hussein for his invasion and annexation of Kuwait the previous year. With Iraq hugely weakened, Iran spent the 1990s consolidating its position in the Gulf, which included preparing for the prospect of closing the strait.
Iran bought three diesel-electric powered Kilo-class attack submarines from Russia in the early 1990s, each capable of carrying up to 18 torpedos and 24 mines. This was the first time ever a country in the region purchased submersibles.
Admiral Ali Shamkhani, commander of all of Iran's naval forces at that time, said in a 1990 speech that the "mission of the submarines is to control the Straits of Hormuz".
In November 1992, the nuclear-powered attack submarine USSTopeka entered the Gulf, the first submarine that was known to have done so, clearly in reaction to Iran's purchase of the Kilos.
Reports in the 1990s stated that Iran's naval build-up in the Gulf was "beyond defensive" and aimed to acquire the capability of shutting the strait, should it end up battling the US navy once again.
"Under an intensive training schedule, including 38 naval exercises staged between October 1995 and March 1996, Iranian scenarios have focused on closing the Straits of Hormuz, sabotaging ports and storming oil platforms and coastal targets," reported Jane's Intelligence Review in 1996.
The Review pointed out that Iran was unlikely to actually close the strait, since that would disrupt its own oil exports, as it would have done a decade earlier. Furthermore, it affirmed that, militarily, Iran remained "hopelessly outmatched" by the United States.
| The most remarkable aspect about Abu Musa is its lack of major military infrastructure and fortification |
Iran took full control over Abu Musa island in April 1992 and built a small $5 million airport that opened in 1996. Jane's reported that Iran-based, American-made, MIM-23 Hawk and Russian-made SA-6 Gainful surface-to-air missiles had been deployed on the island alongside Chinese-made Silkworm anti-ship missiles.
However, upon obtaining commercially released satellite images of Abu Musa taken in late 1999, Jane's noted: "The most remarkable aspect about Abu Musa is its lack of major military infrastructure and fortification, despite the fact that it has been under Iranian occupation for 29 years."
In 1997, Iran hinted once again that it might shut the strait were the US to attack.
"If Iran feels that its security is threatened, it will definitely not allow the region to remain safe for the passage of oil," warned the English-language Tehran Times in May 1997.
The article was written in light of the possibility that the US would have attacked Iran, likely by launching cruise missiles at military targets, at that time if it found evidence implicating Tehran in the Khobar Towers bombing in Saudi Arabia back in June 1996, in which 19 American servicemen were killed.
Much later, in 2006, IRGC General Yahya Rahim Safavi again claimed that Iran could apply pressure on foreign powers by closing the strait.
"The Straits of Hormuz are a point of control and economic pressure on the energy transfer route for those foreign powers that might want to undermine regional security," he said.
His remarks came after Iran tested a new torpedo in the strait, a clear warning that it could disrupt the shipping lanes in the event of any confrontation.
In January 2008, three US warships transiting the strait were approached by five fast IRGC patrol boats and came close to firing on them, potentially causing a confrontation. Tehran denied that it had acted provocatively.
The following July, US Admiral Mike Mullen, then the chairman of the Joint Chiefs of Staff, said he believed the Iranians were capable of interfering with oil traffic going through the strait, but doubted that they could sustain any blockade in the long-term.
In March 2009, two US navy vessels accidentally collided in the strait. While neither sank nor even briefly blocked the strait, the incident resulted in a sudden rise in the price of oil, highlighting how susceptible markets were to any potential closure of Hormuz at that time.
Iranian Vice-President Mohammad-Reza Rahimi threatened to close the strait in December 2011 if Western sanctions on Iran affected its oil exports. Iran also commenced missile tests and naval drills.
US, British and French warships then went to the Gulf and Arabian Sea in a clear move to deter Tehran from potentially making any move to close the strait.
Despite Iranian talk of closing the strait, coupled with the presence of a large US-led naval flotilla in the region at the same time as the large-scale Iranian military exercises, oil prices only rose a paltry two percent. After a few weeks tensions once again simmered down.
Rouhani's warning early this month ultimately amounts to little more than the latest example of half-a-century of fears and threats over the closure of this strategically important channel. It is far from surprising and certainly not unprecedented.
Paul Iddon is a freelance journalist based in Erbil, Iraqi Kurdistan, who writes about Middle East affairs.
Follow him on Twitter: @pauliddon