Following up on an old threat, , blocking a critical sea passage that carries about a fifth of the world’s oil and liquefied natural gas, in retaliation for attacks by and .
As energy markets , the United States is considering escorting ships through the Straits – but that is very difficult to secure, as the Houthis in Yemen showed when they cut off shipping in the Red Sea last year.
According to the United Nations, traffic in the Straits has decreased by 97% since February 28.
Why Iran has closed the Straits now
Iran’s Revolutionary Guards have warned for years that they could close the Straits – even in 2011, one commander said it would be “easier than drinking a glass of water”. The threats were repeated during periods of tensions over sanctions and the nuclear program in 2016 and 2018, and during the Israeli and US raids in June last year.
Although this move was considered a last resort, the war that began on February 28, with the assassination of Iran’s supreme leader, changed the situation. Iranians now describe the conflict as existential, with the Guard increasingly taking over strategic planning.
The Strait of Hormuz, the narrow passage between Iran and Oman that connects the Gulf to the Gulf of Oman, is the only sea outlet for oil and gas producing countries such as Kuwait, Iran, Iraq, Qatar and the United Arab Emirates.
On Monday, oil prices rose temporarily to their highest levels since 2022. High prices could trigger a new cost-of-living crisis, as after Russia’s invasion of Ukraine, the UN warned.
A prolonged conflict could also cause fertilizer shortages, endangering global food security, as about 33% of the world’s fertilizers, including sulfur and ammonia, pass through the Straits.
A prolonged war could also raise fears of a global economic crisis, similar to those that followed the oil crises of the 1970s.
Why are they so hard to protect?
The shipping lanes are just two nautical miles wide, with ships having to turn across Iranian islands and a mountainous coastline, which provides cover for military forces.
Iran’s conventional naval force has been damaged, but the Guard still has plenty of options: fast attack craft, small submarines, mines and jet skis loaded with explosives. Tehran can also produce around 10,000 drones per month.
Escorting three or four ships a day would be feasible in the short term with seven or eight cruisers for air cover, but implementing it continuously for months requires far more resources. Even if Iran’s capabilities with ballistic missiles, drones and surface mines are destroyed, the ships will remain vulnerable to suicide attacks.
What the US and other countries have promised
Donald Trump said on March 3 that the US would provide protection to tankers and has ordered insurance and guarantees for shipping companies.
Emmanuel Macron said that European countries, India and other Asian countries are planning a joint protection mission, but this can only happen when the conflict is over.
France is deploying about a dozen warships, including its aircraft carrier, to the eastern Mediterranean, the Red Sea and possibly the Straits of Hormuz.
The UK is considering options to support merchant shipping across the Straits.
What happened in other straits in the area
Yemen’s Houthis, who have a much smaller arsenal than Iran, have managed to block shipping in the Red Sea and Bab al-Mandab Strait for more than two years, despite the protection of US and EU forces.
Most shipping companies use a route around the southern tip of Africa, while an EU-led force has managed to curb piracy off the coast of Somalia.
Are there alternatives?
The UAE and Saudi Arabia have tried to bypass the Straits by building more oil pipelines, but these are not yet operational, and attacks on a Saudi pipeline in 2019 proved that these alternatives are also vulnerable.
