The U.S. military is blocking the Strait of Hormuz to prevent Iranian oil from reaching global markets, a move that will disrupt global oil flows and affect energy prices.
The U.S. military has announced it will block maritime traffic entering and exiting Iranian ports starting Monday, April 13, at 4:00 PM (CET), preventing nearly 2 million barrels of Iranian oil from flowing into global markets each day. With the Strait of Hormuz blocked, what are the implications for global oil markets?
What Has Been Announced?
After the failure of weekend talks in Islamabad between U.S. and Iranian negotiators, President Trump announced on Sunday, April 12, that the U.S. Navy would begin blocking any ship attempting to enter or exit the Strait of Hormuz. The U.S. Central Command (CENTCOM) clarified that the blockade will only apply to ships coming from or heading to Iran, including all Iranian ports in the Persian Gulf and the Gulf of Oman. The U.S. Navy does not intend to impede the freedom of navigation for ships transiting the Strait to and from non-Iranian ports, but no further details have been provided.
In response, Iran’s Revolutionary Guards warned Trump that any approach of military units to the strait would be considered a violation of the ceasefire. Iran has also threatened to fire on ships in the Gulf or attack infrastructure in Gulf states hosting U.S. forces. Tehran has used control over the Strait as political leverage. While some ships have been allowed to pass, possibly upon payment of a toll, Iran has threatened to have mines planted in the strait as a means of exerting pressure on the Trump administration. Some Iranian lawmakers have even proposed a $2 million toll for each crossing, potentially involving Oman.
Destroying Iran’s Business Model
A blockade of Iranian shipments would cut off a significant source of oil from the global market. In March 2026, Iran exported 1.84 million barrels per day (bpd) of crude oil, and 1.71 million bpd so far in April, compared to an annual average of 1.68 million bpd in 2025, according to Kpler data. Before the war began (on February 28), Iran had loaded nearly record levels of oil onto ships, with over 180 million barrels stored at sea at the beginning of the month. A U.S. blockade of Iranian ports would most likely prevent Iranian ships, which had been able to transit the Strait despite the war, from doing so. The goal is to destroy Iran’s business model. Other ships that remain stuck in port or at sea might begin rerouting supplies via this shipping route.
Trump’s announcement marks a change in approach. Despite military attacks against Iran, U.S. officials had allowed Iranian oil to pass through, attempting to limit pressure on global energy prices. The U.S. had even temporarily suspended sanctions on Iranian oil, allowing its sale abroad for a month, including to the U.S.
How the U.S. Naval Blockade of the Strait of Hormuz Would Work
Trump’s strategy aims to deprive Iran of its primary negotiating leverage and reopen the strait to global trade as quickly as possible, potentially lowering oil prices. The U.S. military has not disclosed how many warships would be involved, whether fighter jets will be used, or if support from Gulf allies is expected.
According to several experts, it is unlikely that U.S. forces would launch missiles or strike oil tankers, as this could cause an environmental disaster. The most likely option is that the U.S. Navy would attempt to force ships to change course through threats.
If this strategy fails, armed boarding teams might be sent to physically seize control of the ships. “Trump wants a quick solution. The reality is that this mission is difficult to carry out alone and likely unsustainable in the medium to long term,” said Dana Stroul, a former senior Pentagon official during the Biden administration, now at the Washington Institute for Near East Policy.
Blocked Strait of Hormuz: What it Means for Oil Flows
Normally, nearly 150 vessels pass through the Strait of Hormuz daily. However, in March, due to the Middle East war, just over 150 vessels passed through the strait for the entire month, according to S&P Global Market Intelligence data. Other ships that managed to pass through likely made arrangements with Iranian authorities and may have paid a toll, as suggested by maritime intelligence company Kpler.
Maritime traffic through Hormuz, heavily restricted by an Iranian blockade since the beginning of the war, remains almost completely stalled despite a ceasefire agreement between Washington and Tehran two weeks ago. According to Kpler, as of April 7, nearly 187 tankers, carrying 172 million barrels of crude oil and refined products, were stationed within the Gulf. Analysts indicate that tanker traffic from Gulf states will not immediately return to pre-war levels, as time is needed to repair some energy infrastructure damaged during the conflict.
