Keys about the Strait of Hormuz: why will it not reopen overnight?

Barcelona / LondonOne of the key points of the fragile ceasefire established between the United States and Iran 48 hours ago is the free movement of maritime traffic through the Strait of Hormuz. A key passage for oil tankers, fertilizers, and dry goods, the strangulation generated by the war threatens the entire world economy. The volume of ship passage has fallen from between 150 and 200 daily on February 27 to six in the last twenty-four hours. The ongoing crisis already has a global economic impact due to the disruption in the supply chains of gas and oil, fertilizers, or helium. The big problem in achieving normalization is that political-diplomatic, military, economic, and geographical factors of two countries with very different agendas intersect, and they have a meeting this Saturday in Islamabad, where the delegations of the United States and Iran are expected to meet. This Thursday, Iran reiterated that it only allows the passage of ships through its territorial waters via an entry and an exit corridor north and south of the island of Larak, where it controls each vessel. And it has even put it on a nautical chart.

Does international law guarantee passage through the Strait of Hormuz?

Beyond the war, the current passage crisis is based on a complex legal void: neither Iran nor the United States have ratified UNCLOS (United Nations Convention on the Law of the Sea of 1982), which allows Tehran to question "transit passage" and attempt to apply the more restrictive "innocent passage". The international community invokes customary law and the jurisprudence of the Corfu Channel case (1949) to argue that no state can prohibit transit in international straits. Iran takes advantage of its position of strength to consolidate a control that could be irreversible, challenging the right of ships to navigate without interference through this vital artery.

Formally, international straits are protected by the principle of freedom of navigation. But this principle is difficult to enforce in a context of war or high tension. In practice, effective control over territory and waters weighs more than legal norms. This allows Iran to limit passage without formal recognition. Although the waters of Hormuz belong to the jurisdictions of Oman, the United Arab Emirates and Iran, freedom of navigation has always been permitted there without tolls or prior permits.

Why can't the strait be reopened overnight?

Because the blockade is not just military or visible. Iran has built a control system that combines armed pressure, administrative control of passage and an indirect economic effect through insurance risk. This means the problem is not simply opening a maritime passage, but restoring an entire ecosystem of trust. Consequently, even if there were a political announcement of reopening or even the announcement of a ceasefire that occurred on Wednesday, maritime and financial operators need real security guarantees. Without this, transit does not resume because the risk remains too high. In the last 24 hours, as far as is known, only one oil tanker and five bulk cargo ships have sailed through the Strait of Hormuz, according to data analysis from ship trackers Kpler, Lloyd's List Intelligence and Signal Ocean.

Is the strait really closed, then?

The Iranian Revolutionary Guard exercises direct and operational control over transit. It has established a system in whichWho controls the passage right now?

The Iranian Revolutionary Guard exercises direct and operational control over transit. It has established a system in which each ship must be previously authorized, with detailed information about its cargo, ownership, and destination. This mechanism turns passage through Hormuz into a case-by-case political decision. Furthermore, authorized ships follow specific routes and are often escorted, while others expose themselves to real risks of interception or attack. The Revolutionary Guard published a map this Thursday that would indicate the aforementioned routes within its territorial waters through which ships can pass. The map indicates an area "of danger restricted to all traffic", where there would be "risk of collision with naval mines".

• If you want to see this map in more detail, open the high-resolution version in another tab.

Why does geography make it so difficult to reopen it militarily?

The strait is a real bottleneck: less than 50 kilometers wide, shallow, and surrounded by Iranian territory. This forces ships to navigate very close to the coast, reducing their maneuverability and reaction time to any threat. Furthermore, the terrain of the coastal territory —with mountains, caves, and cliffs— allows Iran to deploy asymmetric warfare tactics. Relatively simple weapons can be hidden and activated quickly, making it very difficult to neutralize them all. All this makes a military operation extremely complex and costly. It would be necessary to eliminate or neutralize this large quantity of mobile weapon systems, which could also be fired from almost any point in Iran. An armed operation would not be a pinpoint strike, but sustained: escorts, air surveillance, and constant control of the area would need to be maintained. This implies a high military commitment, with a great risk of casualties and escalation. Warships, moreover, can offer partial protection, but they do not solve the problem. The usual volume of traffic is too large to be fully escorted, and each naval convoy, usually enormous vessels loaded with oil and very exposed, requires significant resources. Additionally, military vessels themselves are vulnerable in such a restricted environment.

Why are insurance policies key?

Because maritime transport depends entirely on the financial system. Without insurance, no shipowner can assume the risk of losing a ship valued at tens or hundreds of millions of dollars which, under normal conditions, are mortgaged to large banking corporations. With the conflict, war risk premiums have skyrocketed to levels that make business profitability unfeasible. This leads many ships to prefer to remain anchored rather than operate at a loss or with unmanageable risks. To a large extent, it is the international insurance market that decides. It is the insurers who set the price of risk and determine whether a route is viable or not. Until they consider the situation safe enough, transit will not normalize. It is an economic decision, as much as a political or military one.

What is the real solution?

Most experts agree that there is no military solution. Even if Iran's attack capability were reduced, the residual risk would continue to affect transit. For the situation to return to normal, political de-escalation and credible security guarantees are needed. Only then will insurance premiums be reduced and operator confidence be restored, and even then it would take months to restore the usual pace. There are about two thousand vessels trapped on the other side of the strait, and before the war, about 120 circulated every day.