Key Points
・In July 2026, with war under way in the Middle East, Yemen’s Houthi movement declared a maritime blockade of shipping bound for Saudi Arabia, and a tanker strike and a wave of course changes followed within days.
・The Strait of Hormuz had already ceased to function normally because of the war with Iran, leaving the Red Sea as Saudi Arabia’s main detour, and that detour is now under threat from a group whose interests overlap with Iran’s.
・A state and a non-state armed group have turned two separate straits into a single instrument of pressure, pushing global logistics from an era that optimized for efficiency toward one that has to pay for spare capacity on alternate routes.
A Blockade Aimed at Saudi Ships, and Tankers Turning Back
Yemen’s Houthi movement declared a maritime blockade of shipping bound for Saudi Arabia on July 20. The declaration covers vessels calling at Saudi ports on the Red Sea, and a senior Houthi official said the passage of non-Saudi ships would not be impeded. The group warned that it would target ships heading for Saudi ports in the Bab el-Mandeb strait and asked shipping companies to avoid the waters around it.
Two days later, on July 22, the Saudi oil products tanker Encelia was struck by a missile in the southern Red Sea. Maritime sources said it sent a distress signal near the southern Saudi port of Jizan, and the Saudi government confirmed the attack. The Houthis claimed responsibility and said they had struck several Saudi-linked tankers.
Tankers already sailing in the Red Sea began turning back, waiting, or changing course. On July 22 five ships altered course, two of them heading for the Suez Canal and two moving to wait in open water inside the Red Sea. Three ships carrying Saudi crude for China and India made U-turns.
Aspides, the European Union’s naval mission in the region, advised vessels linked to Israel, the United States, or Saudi Arabia to avoid the Red Sea and the Gulf of Aden until the threat level fell, saying they faced a high risk of attack. Greek shipping authorities issued a warning to their own fleet.
U.S. President Donald Trump said Iran would be held accountable for the series of Houthi attacks. Attention has now moved to a narrower question: how far a blockade aimed only at ships calling at Saudi ports will actually thin out traffic, and how it will change the decisions tanker operators make about where to send their vessels.
Related Articles
How Hormuz Broke Down and the Red Sea Became the Way Out
The East-West Pipeline Carries Crude to Yanbu
As traffic through the Strait of Hormuz thinned, Saudi Arabia shifted the bulk of its crude exports to the Red Sea side of the country.
When war between Iran and the United States and Israel began at the end of February 2026, the Strait of Hormuz, the main artery for the world’s crude, stopped functioning normally within weeks. By March, war risk insurance premiums for some vessels had risen to more than ten times peacetime levels, and commercial traffic was already thinning well before the waterway was physically closed to anything.
To move crude without passing through the strait, Saudi Arabia sent oil across the country through the East-West pipeline, known as Petroline, to the Red Sea port of Yanbu and loaded it onto ships there. This Red Sea route was the main alternative to Hormuz.
The volume a detour can carry, however, is limited. The U.S. Energy Information Administration’s estimates give the scale.
| Category | Volume per day | Nature of the figure |
|---|---|---|
| Oil transiting the Strait of Hormuz | About 20 million barrels | Actual observed flow (first half of 2025) |
| Combined East-West and UAE pipeline capacity | About 4.7 million barrels | Nominal total capacity |
| Of that, spare capacity available for diversion | About 2.6 million barrels | Capacity beyond normal operations |
(All figures from the EIA. Note that the transit figure is an observed flow while the pipeline figures are capacity, so the two are different kinds of numbers.)
Against the volume of oil that had been moving through Hormuz, the pipelines can divert only a little more than a tenth. The Red Sea was an alternative route, but never a route that could handle the same volume.
Who the Houthis Are, and the Red Sea Crisis of 2023-24
This is not the first time the Houthis have stopped ships in the Red Sea.
The Houthis are an armed movement that controls northwestern Yemen, including the capital Sanaa and much of the country’s populated territory. They are counted as part of the Iran-backed “axis of resistance,” receiving weapons and funding from Tehran, but they hold their own decision-making authority and are not regarded as an organization operating fully under Iranian command. In 2015 a Saudi-led coalition intervened to fight them, and after a long war a truce was reached in 2022.
In November 2023 the Houthis began attacking merchant shipping in the Red Sea in the name of solidarity with Palestinians. Many ships switched to the long way around the Cape of Good Hope, and oil moving through the Bab el-Mandeb strait fell from 9.3 million barrels a day in 2023 to 4.1 million barrels a day in 2024, close to a halving, according to the EIA.
When a ceasefire took hold in Gaza in October 2025, the Houthis stopped attacking merchant ships. The current blockade of Saudi-bound traffic means that attacks in the Red Sea, once settled, have started again for reasons unconnected to Palestinian solidarity.
The Strait Called Bab el-Mandeb
Bab el-Mandeb, the setting for this blockade, is the narrow strait linking the Red Sea to the Gulf of Aden.
Together with the Suez Canal, it has formed the spine of the shortest sea route between Europe and Asia. Ships passing through it head north up the Red Sea toward Suez, or south into the Indian Ocean. If the strait becomes unusable, vessels are forced into the long detour around the southern tip of Africa.
The immediate trigger for the blockade declaration is generally taken to be the collapse of the truce between Saudi Arabia and the Houthis in early July. From mid-July the two sides struck each other’s airports and other targets, and the Houthis framed their airport attacks as a response to a Saudi blockade of Yemen’s ports and airports. They make the same claim about the maritime blockade, while Saudi Arabia denies that it is blockading Yemen.
Both sides have been massing forces along the Red Sea coast and up toward the Saudi border. Analysts describe the most serious preparation for war since the 2022 truce. The maritime blockade declared on July 20 marks the point at which tension on land spread to the sea.
How Two Straits Came to Be Linked
The Detour Route Now Carries the Same War Risk as the Route It Replaced
What changed in July 2026 is that the Red Sea, the alternative to Hormuz, became wrapped in the same war risk. Since the war began at the end of February, Saudi Arabia has moved most of its exports through the East-West pipeline to the Red Sea, and global oil supply has leaned on that escape route. The blockade declared on July 20 is aimed at the escape route itself.
How closely Iran and the Houthis are coordinating cannot be established from outside.
Reuters reported on July 16, citing anonymous sources, that Iran had told the Houthis to prepare to close the Red Sea gateway if the United States struck Iran’s power network.
Regional specialists, on the other hand, argue that the Houthis do not simply execute Iranian orders and that this time they acted on a concern of their own, the collapse of their truce with Saudi Arabia.
Either way, the outcome is the same. Even without confirmed coordination, the overlap of interests between a state and an armed group has made two straits into a single risk in the eyes of insurers and the people deciding where to route tankers. The ability to use a strait as a weapon no longer belongs only to the states that control one.
Two Sea Lanes Merge Into a Single Risk on the Insurance Ledger
No warship has to close the sea for the sea to close; it is enough for underwriters to stop writing cover. That mechanism was the subject of our earlier article on the proposed toll for the Strait of Hormuz. What is new now is that the risks of two separate sea lanes are being priced into premiums and routing decisions at the same time.
During the March crisis in Hormuz, war risk premiums for some vessels rose to more than ten times their previous level. Since the July blockade declaration, rates for the southern Red Sea have risen too. Shipowners and insurers assess the risk of a whole voyage rather than of individual straits, which undermines the very premise of a detour: that if one route is dangerous, cargo moves to the other. An alternative route stops working as an alternative.
There is a historical comparison. During the Iran-Iraq war of the 1980s, the “tanker war” saw more than 400 merchant vessels attacked, and the U.S. Navy escorted convoys through the Gulf. Even then, global oil supply never came to a general halt. The difference this time is that the place where Hormuz risk was supposed to be absorbed is under threat at the same moment.
A Blockade That Selects Its Targets Cannot Sort Ships as Cleanly as It Claims
The Houthi blockade does not cover every vessel. It applies to ships calling at Saudi ports, and the group says the strait remains open to everything else. Chinese tankers have reportedly been allowed through. The design resembles a checkpoint that decides which ships may pass rather than a general closure.
The sorting cannot work as declared. In modern shipping, flag state, ownership, operator, cargo, and port history are tangled across borders, so a line around what counts as “Saudi-linked” is hard to draw from the outside, leaving the risk of misidentification and of ships caught in the middle. The EU naval mission advised vessels that had called at Saudi ports to keep their position broadcasts to a minimum. Waters where ships hide their own positions to get through are no longer waters with a functioning premise of safe commercial passage.
Even so, the design of a sea lane that sorts its traffic may be a preview of what is coming. If a ship’s safety comes to depend not on its flag or on international law but on its charterer, its ports of call, and its political associations, the world’s oceans start to split from a single waterway open to all into separate lanes with different levels of safety depending on which camp a vessel belongs to.
The Houthis’ Purpose Is Not a Single One
Houthi behavior can be read in three layers. The first is the official account: retaliation for a Saudi blockade of Yemen’s ports and airports. A Houthi spokesman justified the move with the phrase “an eye for an eye.” The second is the blockade as a bargaining chip for extracting economic and political concessions from Riyadh, a reading specialists also put forward. The third is the alignment of Houthi interests with Iran’s pressure campaign against the United States.
The three layers do not always point the same way. The Houthis have demands of their own that go beyond restoring the truce, and Iran has its own calculations about when to play the Houthi card. Which layer is driving the current blockade shapes how it can end, because it determines whether this is a blockade that a deal with Saudi Arabia can lift, or one that lasts until the war between the United States and Iran is over.
Whichever layer leads, one thing is clear. The capacity to threaten a strait is starting to function as one of the few forms of veto available to a militarily weaker actor against major powers, a way of making it difficult for wars and diplomacy to proceed while ignoring them. That power, though, is exercised by putting merchant ships and their crews in danger. Targeting civilians is a method that no political context turns into something the vocabulary of justification can accommodate.
Naval Escorts Cannot Guarantee That the Sea Stays Open
The defending side faces a structural disadvantage. To shoot down drones and anti-ship missiles worth tens of thousands of dollars, defenders spend interceptors costing millions apiece. This is the asymmetry between cheap attack and expensive defense that the U.S. Navy and others confronted in the Red Sea crisis from 2023.
Navies can also protect only the ships they escort, not the judgments insurers make. Stopping 99 attacks out of 100 still means premiums jump and traffic thins when one vessel is hit. Safety at sea does not end with military capability; it rests on private risk calculation, a domain no navy controls.
That asymmetry is an invitation for others to copy the tactic. Not every strait, however, supports it. It takes a combination of conditions: a narrow lane, few alternative routes, a gap in coastal governance, terrain that hides launchers, and political backing.
The Strait of Malacca, for instance, carries more traffic than Hormuz, but the governing capacity of its littoral states and its geography differ sharply from the Red Sea. The waters where this kind of tactic works are limited.
From an Age of Efficiency to an Age of Redundancy
What this crisis puts in front of the world is the problem of single points of failure. More than 80 percent of global merchandise trade moves by sea, and its main arteries run through a handful of narrow waterways. The more a system is optimized for efficiency, the more a stoppage at one point travels through the whole of it.
A stoppage does not mean that oil ceases to arrive. What happens is that costs swell. Reuters has calculated that a voyage from Yanbu to Taiwan takes 19 days via Bab el-Mandeb but 48 days when rerouted, with fuel costs roughly doubling from about $1.26 million to about $2.87 million, plus a Suez Canal toll of around $1 million.
According to the annual report of the United Nations Conference on Trade and Development, the Red Sea reroutings of 2024 lifted global container shipping demand by 12 percent. It is a world in which moving the same volume of goods requires more ships, more time, and more money.
For Asia’s importing economies, this is not somebody else’s problem, and the exposure varies by fuel. Japan’s crude imports are more than 95 percent dependent on the Middle East, and almost all of that oil passes through the Strait of Hormuz. Its LNG supply, by contrast, has been diversified across more sources, leaving dependence on Hormuz at around 6 percent. The same country’s oil and gas have entirely different levels of resilience to the same crisis.
The effects are already showing up in voyage plans rather than in hypotheticals. Immediately after the blockade declaration, a tanker loaded at Yanbu with naphtha bound for Japan switched to a longer route instead of sailing south through the Red Sea, as Reuters reported.
Redundancy, meaning stockpiles, diversified suppliers, and alternative routes, looks like nothing but cost in normal times. Japan’s oil reserves of more than 200 days and its diversification of LNG suppliers only begin to work as insurance in a crisis like this one. If global trade as a whole starts buying the same insurance, the cost of it will be built permanently into the price of goods.
An Age That Cannot Assume a Sea Open to Everyone
Safety at Sea Has Become Something That Has to Be Designed
The Red Sea developments have arrived in three stages. First, the long-standing worry that Iran might close Hormuz in the event of war. Then the realization in Hormuz that a strait can stop functioning through insurance and private decisions well short of a full closure. And now the extension of that same instrument of war pressure to Bab el-Mandeb, the strait that had served as the way out.
This is not a story of the world’s seas closing all at once. What has changed is that whether a route can be used now depends not only on geography and international law but also on political relationships and private risk assessment.
Logistics in an age that competed on efficiency alone treated safety at sea as a free public good. With that assumption in doubt, questions about what to hold in reserve during peacetime, and about who bears the cost of holding it, are reaching companies and governments, and through electricity bills and gasoline prices, households as well. The next time a strait is named, how deep the crisis runs may come down to whether anyone has an answer ready.
Reference Links
- After Hormuz, Iran turns to Red Sea gateway as new pressure point｜Reuters
- Yemen teeters towards renewed war in shadow of Iran conflict｜Reuters
- More ships change course in Red Sea after Houthi threats, data shows｜Reuters
- Add a month at sea and $2.5 million – what it costs oil tankers to flee Hormuz and Bab el-Mandeb｜Reuters
- Maritime insurance premiums surge as Iran conflict widens｜Reuters
- World Oil Transit Chokepoints｜U.S. Energy Information Administration (EIA)
- Japan’s LNG imports are 6.3% dependent on the Strait of Hormuz｜JETRO (Business Briefs, in Japanese)
- Japan’s oil dependence on the Middle East exceeds 95%｜nippon.com (in Japanese)
