Oil tankers and cargo ships line up in the Strait of Hormuz, photo from March 11, 2026.Image: keystone
The US President has announced a naval blockade of ships heading to or leaving Iranian ports via the Strait of Hormuz. A maritime security expert answers the most pressing questions.
April 13, 2026, 3:15 p.mApril 13, 2026, 3:16 p.m
After negotiations between the warring parties Iran and the USA, mediated by Pakistan, were unsuccessful, US President Donald Trump announced that he would block the Strait of Hormuz.
From Monday, 4 p.m. Swiss time, the US Navy will no longer allow ships to sail through the strait – regardless of whether they are heading to or leaving an Iranian port. Trump announced this via his own short message service Truth Social.
For the moment, however, Iran controls the strait, which is so important for world trade. So there is a risk of a double blockade.
What is the current situation on the Strait of Hormuz?
“The Strait of Hormuz is currently only passable under Iran’s conditions,” says Johannes Peters, who heads the Maritime Strategy and Security Department at the Institute for Security Policy at Kiel University, to watson. Ships wanting to transit the strait would have to contact Iran in advance, coordinate with its armed forces and pay a fee of $2 million.
Peters attests that Iran has acted cleverly. He made it clear that he can influence the strait and that he is able and willing to damage ships there. “In doing so, Iran has created a climate in which no merchant ship would dare to cross the strait without complying with Iran’s conditions,” says Peters.
To person
Johannes Peters has been Head of Department for Maritime Strategy and Security at the Institute for Security Policy (ISPK) at the Christian Albrechts University in Kiel since 2021. His research focuses, among other things, on current maritime conflicts. The ISPK describes itself as a “leading competence center” for discussing the most important security policy challenges in the maritime area.
Image: zvg
What does Trump want to do with the blockade – and what are the possible consequences?
Peters sees two considerations at work behind Trump’s plans to block the blocked Strait of Hormuz itself. Firstly, the US President wants to take Iran’s most important means of pressure out of its hands.
And secondly: “The USA also wants to deprive Iran of the opportunity to export its own oil from Iran to the world in order to weaken it economically.”
Peters doubts that such a weakening of Iran will be of any significant benefit to the USA: “Iran has been used to an economy of scarcity for decades. If the population suffers, the regime doesn’t really care as long as it is firmly in the saddle.” For Peters it is clear:
“Iran is more capable of suffering than the global economy.”
In addition, the US strategy of blocking the Strait of Hormuz carries the risk of further escalation. Because: Iranian oil exports primarily go to India and China.
If the USA were to block these oil deliveries, they would risk an open conflict, especially with China, says Peters: “It is questionable to me whether the USA is really willing to accept a military clash with the Chinese navy in the Indian Ocean.”
What would a blockade actually look like?
Even if the USA actually gets serious about the double blockade, very practical questions arise. How do you block an already blocked sea passage? Where will the US Navy position itself?
“I don’t assume that the US will actually set up this blockade in the immediate vicinity of the Strait of Hormuz,” says Peters. And further: “In any case, they will operate beyond the range of Iranian missiles and drones.”
The USA benefits from the fact that merchant and tank ships move very slowly and their routes are known. “So there is no need to set up the blockade directly in front of the Strait of Hormuz.”
How can you stop a ship from continuing its journey? “You block a ship by calling it on the radio and demanding that it stop,” says Peters. If the ship’s crew refuses to comply with this request, there are various options.
“The USA would then first try to board the ships with specially trained units. This is done either with the help of helicopters or speedboats.” The USA has acted similarly in the past with Russian or Venezuelan ships. Peters states: “Shelling or sinking the ships is the last resort and would only be conceivable after the crews had been evacuated.”
Is Trump’s blockade announcement just a bluff?
Iran described Trump’s announcement of a naval blockade of the Strait of Hormuz as a “bluff”. Peters says: “It is difficult to assess whether the blockade threat is a bluff.” The blockade on ships entering or leaving Iranian ports is set to take effect at 4 p.m. on Monday. “Perhaps Trump will announce this afternoon that Iran has now made concessions on the basis of which negotiations can continue,” speculates the maritime security expert.
An Iranian daily newspaper has the title “See-Bluff”, photo from April 13, 2026.Image: keystone
Peters’ verdict is clear: “Iran is acting much more skillfully in this conflict than the USA.” After the failed negotiations at the weekend, the Iranian side emphasized that the communication channels would remain open. “This corresponds to the normal procedure and places the ball in the USA’s field,” says Peters.
The USA, on the other hand, is in a bad position with its strategy: “The announcement of the naval blockade is another example of how badly the USA has lost its way.” According to Peters, the most recent announcements about the Strait of Hormuz are exemplary of Trump’s conduct of war in Iran: “The USA lacks a clear strategic goal – they probably didn’t have one from the start.”
What consequences would a US blockade have for the global economy?
The Strait of Hormuz is one of the most important routes for global oil trade. The price of oil rose to over a hundred dollars per barrel due to the possible double blockade. Even if it is a difficult signal politically, Peters says:
“The world can live much better with a reliable Iranian regime across the Strait of Hormuz than with a permanent blockade of energy exports across the Strait of Hormuz.”
The USA would be hit less hard by the blockade than Europe, Asia or Africa, says Peters. “They are largely energy self-sufficient, but with their questionable military actions they are making the whole world pay.” Peters therefore assumes that this will also increase the pressure from Trump’s allies – “if he still has any.”