The Strait with maritime political boundaries (2004)The strait separatesIran to the north and theMusandam Governorate ofOman and theUnited Arab Emirates to the south. (1892 map)The strait as seen from an airliner at 35,000 feet (10,668 m). Musandam is in the foreground.
TheStrait of Hormuz (/hɔːrˈmuːz/Persian:تنگهٔ هُرمُزTangeh-ye Hormozlistenⓘ,Arabic:مَضيق هُرمُزMaḍīq Hurmuz) is astrait between thePersian Gulf and theGulf of Oman. It provides the only sea passage from the Persian Gulf to the open ocean and is one of the world's most strategically importantchoke points.[1] It has been so for centuries, with vast hinterlands rich in luxury trade good, but no easy access to lucrative trading ports.Babur's memoirs recount how almonds had to be carried from the distantFerghana region inCentral Asia to Hormuz to reach markets.[2]
During 2023–2025, 20% of the world'sliquefied natural gas and 25% of seaborneoil trade passes through the strait annually. As of June 2025[update], the strait has never been closed during Middle East conflicts, unlike theStraits of Tiran,[5] though Iran threatens to close the strait,[6][7] and preparations to mine it have been undertaken.[8]
Popular etymology derives "Hormuz" from theMiddle Persian pronunciation of the name of theZoroastrian godAhura Mazda. Alternatively, it has been suggested that the name derives from Hur-Muz 'Place ofDates'.[9] Yet another possibility is that it comes from ὅρμοςhormos, the Greek word for 'cove, bay'.[10] A theory claims that the strait of Hormuz may have been named afterIfra Hormizd, the mother ofKing Shapur II of Persia, who ruled between 309 and 379 AD.[citation needed]
The opening to the Persian Gulf was described, but not given a name, in thePeriplus of the Erythraean Sea, a 1st-century mariner's guide:
At the upper end of these[which?] Calaei islands is a range of mountains called Calon, and there follows not far beyond, the mouth of the Persian Gulf, where there is much diving for the pearl-mussel. To the left of the straits are great mountains called Asabon and to the right there rises in full view another round and high mountain called Semiramis; between them the passage across the strait is about six hundred stadia; beyond which that very great and broad sea, the Persian Gulf, reaches far into the interior. At the upper end of this gulf, there is a market-town designated by law called Apologus, situated near Charaex Spasini and the River Euphrates.
— Periplus of the Erythraean Sea, Chapter 35
In the 10th–17th centuries AD, the Kingdom ofOrmus, which seems to have given the strait its name, was located here. Scholars, historians and linguists derive the name "Ormuz" from the localPersian wordهورمغHur-mogh meaning date palm.[11] The resemblance of this word to the name of theZoroastrian godهرمزHormoz (a variant ofAhura Mazda) has resulted in the belief[citation needed] that these words are related.
To reduce the risk of collision, ships moving through the strait follow atraffic separation scheme (TSS): inbound ships use one lane, outbound ships another, each lane being two miles wide. The lanes are separated by a two-mile-wide "median".[12]
In 1959, Iran altered the legal status of the strait by expanding its territorial sea to 12 nmi (22 km) and declaring it would recognize only transit byinnocent passage through the newly expanded area.[16] In 1972, Oman also expanded its territorial sea to 12 nmi (22 km) by decree.[16] Thus, by 1972, the Strait of Hormuz was completely "closed" by the combined territorial waters of Iran and Oman. During the 1970s, neither Iran or Oman attempted to impede the passage of warships, but in the 1980s, both countries asserted claims that were different from customary (old) law. Upon ratifyingUNCLOS in 1989, Oman submitted declarations confirming its 1981 royal decree that only innocent passage is permitted through its territorial sea. The declarations further asserted that prior permission was required before foreign warships could pass through Omani territorial waters.[16] Upon signing the convention in 1982, Iran entered a declaration stating "that only states parties to the Law of the Sea Convention shall be entitled to benefit from the contractual rights created therein", including "the right of transit passage through straits used for international navigation". In 1993, Iran enacted a comprehensive law on maritime areas, provisions of which conflict with UNCLOS provisions, including a requirement that warships, submarines, and nuclear-powered ships obtain permission before exercising innocent passage through Iran's territorial waters. The US does not recognize any of the claims by Oman and Iran and has contested each of them.[16]
Oil trade through the strait by origin and destination, 2014–18
During 2023–2025, 20% of the world'sliquefied natural gas and 25% of seaborneoil trade passes through the Strait, illustrating its important location for trade.[4][17][7]
According to theU.S. Energy Information Administration, in 2011, an average of 14 tankers per day passed out of the Persian Gulf through the strait carrying 17 million barrels (2,700,000 m3) of crude oil. More than 85% of these crude oil exports went to Asian markets, with Japan, India, South Korea and China the largest destinations.[13] In 2018, 21 million barrels a day passed through the strait, worth $1.2 billion at 2019 prices.[18]
TheTanker War phase of theIran–Iraq War started when Iraq attacked the oil terminal and oil tankers at Iran'sKharg Island in early 1984.[19][20]Saddam Hussein's aim in attacking Iranian shipping was, among other things, to provoke the Iranians to retaliate with extreme measures, such as closing the Strait of Hormuz to all maritime traffic, thereby bringing American intervention.[19] Iran limited the retaliatory attacks to Iraqi shipping, leaving the strait open.[19]
Operation Praying Mantis was an attack on 18 April 1988 by theUnited States Armed Forces within Iranian territorial waters in retaliation for theIranian navalmining ofinternational waters in thePersian Gulf during theIran–Iraq War and the subsequent damage to an American warship. The U.S. Navy attacked with several groups of surface warships, plus aircraft from the aircraft carrierUSSEnterprise, and her cruiser escort,USSTruxtun. The attack began with coordinated strikes by two surface groups.
In May 2020, Iran launched missiles at one of their own ships in a friendly fire accident, killing 19 sailors.[23] On 2 June 2021, theIRISKharg, a modifiedOl-classreplenishment oiler of the Iran Navy, sank in the Strait of Hormuz after catching fire. It was the navy's largest vessel.[24]
On 28 April 2015,IRGCN patrol boats contacted theMarshall Islands-flaggedcontainer shipMaersk Tigris, which was westbound through the strait, and directed the ship to proceed further into Iranian territorial waters, according to a spokesman for the U.S. Defense Department. When the ship's master declined, one of the Iranian craft fired shots across the bridge ofMaersk Tigris. The captain complied and proceeded into Iranian waters near Larak Island. The US Navy sent aircraft and a destroyer,USSFarragut, to monitor the situation.[25]Maersk says it agreed to pay an Iranian company $163,000 after an Iranian court ruling over a dispute about 10 container boxes transported to Dubai in 2005. An appeal court raised the fine to $3.6 million.[26]
On 4 January 2021, theTasnim News Agency reported that a South Korea-flagged oil vessel headed fromSaudi Arabia to theUnited Arab Emirates was seized for allegedly causing pollution violations. The ship was said to be carrying roughly 7,000 tons of ethanol. South Korea refused to comment on the accusation of causing oil pollution in the Strait of Hormuz. The ship,Hankuk Chemi, was headed to the UAE port Fujairah after loading oil from Jubail, Saudi Arabia on 2 January 2021, as per ship-tracking data gathered by Bloomberg.[27]
In April 2024, the Iranian Navy seized[28]MSC Aries, aPortuguese-flagged container ship sailing through theGulf of Oman off the UAE coast of the Emirati port city ofFujairah, then steered the container ship through the strait, with 25 personnel on board, claiming that it had violated maritime laws.[29] The crew of 25 included 17 Indian nationals, Filipinos, Pakistanis, a Russian, and an Estonian.[30]
As of 2019, the U.S. Defense Intelligence Agency estimated that Iran possessed over 5,000 naval mines capable of rapid deployment via high-speed boats.[8] In June 2025, it was reported that U.S. intelligence detected, possibly through satellite imagery or human informants, that Iranian military forces loaded naval mines onto vessels in the Persian Gulf, an act which was interpreted as a preliminary step to blockading the strait.[8] The mines were ultimately not deployed, though their presence raised alarms in Washington about Tehran's intent to escalate the conflict. It is unclear whether the mines were later removed.[8]
Naval stand-offs between Iranian speedboats and US warships in the strait occurred in December 2007 and January 2008. U.S. officials accused Iran of harassing and provoking their naval vessels, but Iran denied the allegations. On 14 January, U.S. Navy officials appeared to contradict the Pentagon version of the 16 January event, in which the Pentagon had reported that U.S. vessels had almost fired on approaching Iranian boats. The Navy's regional commander, Vice Admiral Kevin Cosgriff, said the Iranians had "neither anti-ship missiles nor torpedoes" and he "wouldn't characterize the posture of theUS 5th Fleet as afraid of these small boats".[31] On 29 June, the commander ofIran's Revolutionary Guard,Mohammad Ali Jafari, said that if eitherIsrael or the US attacked Iran, it would seal off the strait to wreak havoc in the oil markets. Cosgriff warned that such Iranian action would be considered an act of war, and the U.S. would not allow Iran to hold hostage a third of the world's oil supply.[32] On 8 July, Ali Shirazi, a mid-level clerical aide to Iran's Supreme LeaderAyatollah Ali Khamenei, was quoted telling the Revolutionary Guards, "The Zionist regime is pressuring White House officials to attack Iran. If they commit such a stupidity,Tel Aviv and U.S. shipping in the Persian Gulf will be Iran's first targets and they will be burned."[33]
In the last week of July, in Operation Brimstone,[34] dozens of US, and naval ships from other countries, came to undertake joint exercises for possible military activity in the shallow waters off the coast of Iran. By 11 August, more than 40 U.S. and allied ships were en route to the strait.[35]
On 27 December 2011, IranianVice PresidentMohammad Reza Rahimi threatened to cut off oil supply from the strait should economic sanctions limit, or cut off, Iranian oil exports.[36] AUS Fifth Fleet spokeswoman said the Fleet was "always ready to counter malevolent actions", whilst AdmiralHabibollah Sayyari of theIran Navy claimed cutting off oil shipments would be "easy".[37] Despite an initial 2% rise in oil prices, markets ultimately did not react significantly to Iran's threat, with oil analyst Thorbjoern Bak Jensen concluding "they cannot stop the flow for a longer period due to the amount of U.S. hardware in the area".[38]
On 3 January 2012, Iran threatened to take action if the U.S. Navy moved an aircraft carrier back into the Persian Gulf. Iranian Army chiefAtaollah Salehi said the US had moved a carrier out of the Persian Gulf because of Iran's naval exercises, and Iran would take action if the ship returned. "Iran will not repeat its warning...the enemy's carrier has been moved to theGulf of Oman because of our drill. I recommend and emphasize to the American carrier not to return to the Persian Gulf", he said.[39] U.S. Navy spokesman Commander Bill Speaks responded that deployment of U.S. military assets would continue as has been the custom stating: "The U.S. Navy operates under international maritime conventions to maintain a constant state of high vigilance in order to ensure the continued, safe flow of maritime traffic in waterways critical to global commerce."[40] While earlier statements from Iran had little effect on oil markets, coupled with new sanctions, later comments drove crude futures higher, up over 4%. Pressure on prices reflected a combination of uncertainty driven further by China's response – reducing oil January 2012 purchases from Iran by 50% compared to 2011.[citation needed]
By January 2012, U.S.-led sanctions began to show economic effects, as the Iranian currency lost 12% of its value. Further pressure on Iranian currency was added by French Foreign MinisterAlain Juppé who was quoted as calling for more "strict sanctions" and urged EU countries to follow the US in freezing Iranian central bank assets and imposing an embargo on oil exports.[41]
On 9 January 2012, Iranian Defense MinisterAhmad Vahidi denied that Iran had ever claimed it would close the strait, saying that "Iran is the most important provider of security in the Strait... if one threatens the security of the Persian Gulf, then all are threatened."[42] Iran's Foreign Ministry confirmed on 16 January it had received a letter from the US. Authorities were considering whether to reply, although the contents of the letter were not divulged.[43] The US had previously announced its intention to warn Iran that closing the strait is a "red line" that would provoke an American response.[44] Gen.Martin E. Dempsey, chairman of theJoint Chiefs of Staff, said the US would "take action and re-open the Strait", which could be accomplished only by military means, including minesweepers, warship escorts and potentially airstrikes. Defense SecretaryLeon E. Panetta told troops that the US would not tolerate Iran closing the strait. Nevertheless, Iran continued to discuss the impact of shutting the strait on oil markets, saying any disruption of supply would cause a shock "no country" could manage.[45]
By 23 January, aflotilla had been established by countries opposing Iran's threats to close the strait.[46] These ships operated in the Persian Gulf andArabian Sea off the coast of Iran. The flotilla included three American aircraft carriers, three destroyers, seven British warships, including the destroyerHMS Daring[47][48] and fourType 23 frigates, and the French frigateLa Motte-Picquet.[49] On 24 January, tensions rose further after theEuropean Union imposed sanctions on Iranian oil. A member of Iran's parliament said, "If any disruption happens regarding the sale of Iranian oil, the Strait...will definitely be closed".[50]
In July 2018, Iran again made threats to close the strait, citing looming American sanctions after the U.S.withdrew from theJCPOA deal.[51] In August, Iran test-fired a ballistic missile. According to the officials, the anti-shipFateh-110 Mod 3 flew over 100 miles on a flight path over the strait to a test range in the Iranian desert. "It was shore-to-shore", said a U.S. official.[52]
On 22 April 2019, the U.S. ended the oil waivers, which had allowed some of Iran's customers to import Iranian oil, without risking financial penalties as part of U.S. economic sanctions. Al Jazeera quoted Major-GeneralMohammad Bagheri of the Iranian Armed Forces, stating "We are not after closing the Strait of Hormuz but if the hostility of the enemies increases, we will be able to do so...[53] If our oil does not pass, the oil of others shall not pass the Strait of Hormuz either".[54]
Iran has persistently attacked vessels and seized ships amidst political issues.[30][55] On 13 June 2019, the oil tankersFront Altair andKokuka Courageous were rocked by explosions shortly before dawn; the crew of the latter reported seeing a flying object strike the ship. They were rescued by the destroyerUSS Bainbridge while the crew of theFront Altair were rescued by Iranian ships. U.S. secretary of stateMike Pompeo issued a statement accusing Iran of the attacks, Iran denied this calling it afalse-flag attack.[56]
In July 2019, a Stena Bulk Tanker,Stena Impero, sailing under a British flag, was boarded and captured by Iranian forces.[57] The spokesman for Iran's Guardian Council, Abbas Ali Kadkhodaei, was quoted as describing the seizure as a "reciprocal action". This was presumed to be in reference to the seizure of an Iranian tanker,Grace 1, bound for Syria inGibraltar a few days prior.[58]
In 2020, France deployed about 600 troops at sea and in the air under the CTF474 to protect maritime trade, regional business, and to ease local tensions. Since the first week of April 2020, the operation combines the Dutch frigate Ruyter, the French frigate Forbin, and one French airplane ATLANTIC2 (ATL2).[59]
On 14 June, Iran reportedly issued a threat to block the strait in response to Israeli attacks targeting its military and nuclear infrastructure.[6][60] TheFinancial Times reported that such action could cause oil prices to surge beyond the recent 7–14% increases, possibly exceeding $100 to $150 per barrel.[61] This would likely fuel global inflation and contribute to an economic downturn. Analysts emphasized the vulnerability of regional exporters, noting that "Saudi Arabia, Kuwait, Iraq and Iran are wholly locked into one tiny passage for exports." The strait handles 18-19 million barrels per day, nearly 20% of global oil consumption, including crude, condensates, and fuel.[62][63] Analysts have warned that Iran could suffer severe consequences from any attempt to block the strait. "Iran's economy heavily relies on the free passage of goods and vessels through the seaway, as its oil exports are entirely sea-based," analysts from JP Morgan explained. Closing the strait could strain Iran's crucial energy trade with China, its only major oil customer.[62][64] U.S. Secretary of State Marco Rubio also warned Iran against attempting to shut down the strait, stating that such a move would be "economic suicide" for the Islamic Republic, as the waterway is vital for its exports.[65] On 17 June, two oil tankers collided in the strait, though reports did not suggest that this was a security-related incident.[66] The vessels involved were theFront Eagle, carrying crude oil from Iraq to China, and theAdalynn, which was unladen and en route to the Suez Canal. Both caught fire on deck, but no oil spill occurred. All crew members aboard theAdalynn were safely evacuated by the UAE coast guard.[67]
After theUnited States strikes on Iranian nuclear sites on 22 June, the Iranian Parliament voted to close the strait.[68] A final decision rests with Iran'sSupreme National Security Council.[69] Revolutionary Guards commanderEsmaeil Kousari confirmed that shutting the strait would be executed "whenever necessary", to protect nationalsovereignty and deter further foreign aggression.[70][71] The potential closure of the strait, through which 20% of the world's oil supply transits, would significantly disrupt global energy markets. Such a move could cause oil prices to increase and risk destabilizing the global economy, given the strait's critical role as a maritime chokepoint for crude oil, liquefied natural gas, and otherpetroleum products.[72] On 23 June 2025,oil prices were below $70 again (7% lower than on 20 June), indicating that theoil market viewed the US strikes, and Iran's response (the strait remaining open, and2025 Iranian strikes on Al Udeid Air Base), as inconsequential.[73]
Millennium Challenge 2002 was a major war game exercise conducted by US armed forces in 2002. It simulated an attempt by a country (likely to be Iran) to close the strait. The assumptions and results were controversial. Iran's simulated strategy beat the materially superior US armed forces.[74]
A 2008 article inInternational Security contended that Iran could seal off or impede traffic in the strait for a month, and an attempt by the U.S. to reopen it would be likely to escalate the conflict.[75] In a later issue, however, the journal published a response which questioned key assumptions and suggested a much shorter timeline for re-opening.[76]
Moreover, due to Iran's own dependence on oil exports through the strait as well as imports, (due to its inability to refine oil on its own) a closure of the strait is unlikely.[77] Not only Iran's own dependence on the strait for imports and exports is indicative that a prolonged closure is unlikely, but also the dependence of its allies on the trade that flows through it suggest the logistical infeasibility of such closure.[78] Aneoclassical-realist analysis describes Iranian policy regarding the strait as "double-faced": in non-existential threat environments Tehran tends to act as a security provider by keeping the strait open, whereas under threats perceived as existential it takes calculated risks and incorporates the waterway into a widerdeterrence andbrinkmanship strategy.[79] This interpretation portrays Iran as a reactive actor that employs interference or brinkmanship to gain concessions and trigger de‑escalatory measures from the international community.[80]This literature also emphasizes that Iran’s strategy with respect to the strait is constrained by its own reliance on the waterway, that of key partners, material limits and sanctions, which lowers its freedom to take risks and suggests that any prolonged closure would be particularly damaging for Iran itself and its allies.[81][82][83][84]
In December 2011, Iran's Navy began a ten-day exercise in international waters along the strait. Iranian Rear AdmiralHabibollah Sayyari stated that the strait would not be closed during the exercise; Iranian forces could easily accomplish that but such a decision must be made at a political level.[85][86] CaptainJohn Kirby, a Pentagon spokesman, was quoted in December 2011 saying: "Efforts to increase tension in that part of the world are unhelpful and counter-productive. For our part, we are comfortable that we have in the region sufficient capabilities to honor our commitments to our friends and partners, as well as the international community." Suzanne Maloney, an expert at the Brookings Institution, said, "The expectation is that the U.S. military could address any Iranian threat relatively quickly."[87]General Martin Dempsey, Chairman of the Joint Chiefs of Staff, said in 2012 that Iran "has invested in capabilities that could, in fact, for a period of time block the Strait of Hormuz." He stated, "We've invested in capabilities to ensure that if that happens, we can defeat that."[88]
A May 2012 article by Nilufer Oral, a Turkish researcher ofmaritime law, concludes that both theUNCLOS, which came into effect in 1994; and the 1958Convention on the High Seas would be violated if Iran followed through on its threat to block passage of vessels, such as oil tankers, and that the act of passage is not related in law to the imposition of economic sanctions. The article further asserts that a coastal state may prevent "transit or non-suspendable innocent passage" only if: 1) there is threatened or actual use of force, occurring during passage, against the sovereignty, territorial integrity, or political independence of a state bordering the strait; or 2) the vessel in any other way violates the principles of international law as embodied in theCharter of the United Nations.[89]
In June 2012,Saudi Arabia reopened the Iraq Pipeline through Saudi Arabia (IPSA), which was confiscated fromIraq in 2001 and travels from Iraq across Saudi Arabia to aRed Sea port. It will have a capacity of 1.65 million barrels (262,000 m3) per day.[92]
In July 2012, theUAE began using the newHabshan–Fujairah oil pipeline from theHabshan fields inAbu Dhabi to theFujairah oil terminal on theGulf of Oman, effectively bypassing the Strait of Hormuz. It has a maximum capacity of around 2 million barrels (320,000 m3) per day, over three-quarters of the UAE's 2012 production rate. The UAE is also increasing Fujairah's storage and off-loading capacities.[92][93] The UAE is building the world's largest crude oil storage facility in Fujairah with a capacity of holding 14 million barrels (2,200,000 m3) to enhance Fujairah's growth as a global oil and trading hub.[94] The Habshan – Fujairah route secures the UAE's energy security and has the advantage of being a ground oil pipeline transportation which is considered the cheapest form of oil transportation and also reduces insurance costs as oil tankers would no longer enter the Persian Gulf.[95]
In a July 2012Foreign Policy article,Gal Luft compared Iran and the Strait of Hormuz to theOttoman Empire and theDardanelles, a choke point for shipments ofRussian grain a century ago. He indicated that tensions involving the Strait of Hormuz are leading those currently dependent on shipments from the Persian Gulf to find alternative shipping capabilities. He stated that Saudi Arabia was considering building new pipelines toOman andYemen, and that Iraq might revive the disused Iraq–Syria pipeline to transport crude oil to the Mediterranean. Luft stated that reducing Hormuz traffic "presents the West with a new opportunity to augment its current Iran containment strategy."[92]
^"World Oil Transit Chokepoints"(PDF). U.S. Energy Information Administration. 25 July 2017.Archived(PDF) from the original on 21 May 2019. Retrieved13 June 2019.
^abAlejandra Roman & Administration."Strait of Hormuz". The Encyclopedia of Earth.Archived from the original on 5 April 2016. Retrieved2 June 2015.
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