Why Strait of Hormuz is key and what Iran can do

In the aftermath of the United States striking bombing three Iranian nuclear research facilities, Iran, in retaliation, is considering closing the Strait of Hormuz, a critical shipping route for supply of oil and natural gas from the Middle East to other parts of the world.

Connecting the Persian Gulf to the Gulf of Oman and thereon to the Arabian Sea and the Indian Ocean, the Strait of Hormuz is one of the world's most critical chokepoints, through which a fifth of global oil and gas supply flows.

Closing this channel will impact the global oil supply chain and the shipping industry.

In simple geographical terms. A strait is a narrow, naturally formed strip of waterway that connects two larger water bodies like seas or oceans. Straits are considered strategically important for trade and military operations, as they can control access of maritime traffic between regions.

The Strait of Gibraltar, which connects the Atlantic Ocean and the Mediterranean Sea and the Strait of Malacca, which connects the Indian Ocean and the Pacific Ocean are other examples.

The topography of Strait of Hormuz

Located between the Oman’s Musandam Peninsula that abuts the United Arab Emirates (UAE) and Iran, the strait provides the only sea link for Iraq, Kuwait, Bahrain and Qatar, and access to some of the ports of Saudi Arabia, Iran and the UAE. It is 167 kms long and its width varies from 33 kms to 96 kms, falling in the territorial waters of both Oman and Iran.

Some areas of the strait are unsuitable for large tankers because of shallow depth and the presence of islands. The Strait contains eight major islands, seven of which are controlled by Iran, which also has major ports on its mainland on either side of the strait.

To reduce the risk of collision, ships moving through the Strait follow a Traffic Separation Scheme (TSS). Ships entering the Persian Gulf use one corridor while those existing the gulf use another. Each corridor is 3.5 kms wide and are separated by lane of similar width.

 Why is it important

The Persian Gulf region accounts for a significant chunk of global oil trade. According to the US Energy Information Administration (EIA), flows through the Strait of Hormuz in 2024 and the first quarter of 2025 made up more than one-quarter of total global seaborne oil trade and about one-fifth of global oil and petroleum product consumption. In addition, around one-fifth of global liquefied natural gas trade also transited the Strait of Hormuz in 2024, primarily from Qatar.

Every day 17 to 21 million barrels of crude, condensate and fuels flow through the strait. Members of the Organisation of the Petroleum Exporting Countries (OPEC) – Saudi Arabia, Iran, the UAE, Kuwait and Iraq – export most of their crude through the strait, mainly to Asia.

Crude is transported from its source to overseas destination by seaborne bulk carriers, that is, oil tankers of various sizes that can carry up to several million barrels at a time, or in some cases was between Russia and Europe, through inland pipelines. Air transport for crude is out of question.

Closing the strait would reduce supply, triggering an oil price spike and immediate inflationary effect across the globe. About 30 per cent of Indian oil imports are sources through this strait, while 90 percent of China’s oil imports are from Iran. China’s is a strong supporter of Iran, while India’s relations with Iran have also been friendly.

If Iran shuts down the strait but allows its own vessels to pass, it risks upsetting other affected gulf states that have been critical of Israel’s recent strikes on Iran, and they may look for means to safeguard their interests. If Iran’ whose economy depends majorly on oil exports choses to keep the strait closed to its own ships too, China would be the most affected country.

India, in the immediate future, may not be adversely affected since it has multiple sources of energy originating from areas other than the Persian Gulf and also because of a five-week buffer stock. The bulk of its natural gas imports are from Qatar and UAE, which do not use the strait.

Are there alternate supply routes for oil

There is no sea route alternative to the Strait of Hormuz, but there is a limited option for some OPEC nations of transporting crude through pipelines or rail to ports located on the Red Sea to the west of Saudi Arabia or to the Gulf of Oman, south of the strait.

The East-West Crude Oil Pipeline in Saidia Arabia that connects the Persian Gulf to the Red Sea, the Iraq Pipeline through Saudi Arabia (IPSA), that travels from Iraq across Saudi Arabia to the Red Sea and the Habshan–Fujairah oil pipeline from the Habshan fields in Abu Dhabi to the Fujairah oil terminal on the Gulf of Oman are land alternatives.

The combined capacity of these three pipelines is estimated to be around 8 million ballers per day, far short of the daily seaborne volume. Diverting additional crude through the pipelines would also add to operational, technical and logistical issues.

How can Iran block the strait

The Strait of Hormuz has never been blocked before despite wars and other incidents that the region has witnessed. The territorial waters of Iran and Oman, over which they can exercise sovereignty, extend 22 kms into the sea. But in places where these overlap, the distance is evenly divided.some portions of the shipping lanes fall totally in Iranian waters while some in Omani jurisdiction

Iran has no legal authority to direct merchant traffic not to navigate the waters and will have to rely on military means. This could include laying mines in the sea or using its warships and shore based missiles to enforce any blockade.

The Iranian Navy operates 19 submarines, seven frigates, five corvettes, 20 fast attack craft and six patrol boats, besides other vessels, which it can use to stop, detain or attack ships. While these may not be top of the line warships, these may suffice to deal with unarmed merchantmen.

Any blockade of the strait by Iran would require diplomatic of military means end. The US Fifth Fleet, based in Bahrain, is tasked for operations in the Persian Gulf and the Arabian Sea. It includes the aircraft carrier, USS Dwight D. Eisenhower along with a number of heavily armed guided missile destroyers and frigates. The possibility of Iran blocking the strait has been war-gamed by the US in the past.