WASHINGTON: Oil prices surged around 9 percent on Monday after US President Donald Trump announced the reinstatement of a US naval blockade on Iranian ports and Washington and Tehran exchanged fresh military strikes, heightening concerns over security in the Strait of Hormuz.
By around 1820 GMT, Brent crude futures had risen 9.1 percent to $82.90 a barrel, while US benchmark West Texas Intermediate (WTI) climbed 9.1 percent to $77.87 a barrel.
The sharp rise came as tensions intensified around the Strait of Hormuz, one of the world’s most important oil shipping routes.
Trump announces naval blockade
Trump announced that the United States would reinstate a naval blockade of Iranian ports in the Strait of Hormuz, saying the strategic waterway would remain open to international shipping while Iranian vessels and their customers would be prevented from entering or leaving.
“The Hormuz Strait is open, and will remain open, with or without Iran,” Trump wrote on his Truth Social platform.
“We are reinstating the Iranian blockade, so named because it is only stopping Iran’s ships or customers from entering or leaving. All other countries will have fair and open use of the Strait,” he added.
Trump also said the United States would become “the guardian of the Hormuz Strait” and would be reimbursed for providing security.
“As a matter of fairness, [the United States] will be reimbursed, at the rate of 20 percent on all cargo shipped, for any and all costs necessary to do the job of providing safety and security to this very volatile section of the world,” he wrote.
“The process and formation will begin immediately,” Trump added.
— Rapid Response 47 (@RapidResponse47) July 13, 2026
US military to resume blockade on Tuesday
Later on Monday, US Central Command (CENTCOM) said US forces would begin enforcing the renewed blockade on Tuesday.
In a statement, CENTCOM said US forces “will resume blockading maritime traffic entering and exiting Iranian ports on July 14 at 4 pm ET” (2000 GMT).
— U.S. Central Command (@CENTCOM) July 13, 2026
Earlier in the day, Trump told Fox News in a phone interview that the United States would probably take control of the Strait of Hormuz and should be paid for protecting the strategically important waterway.
“We’re going to keep the strait, and we’ll probably run it. We’ll become the guardian of the Strait. Maybe we’ll call it the guardian angel of the strait. And we should be reimbursed for that,” Trump said.
“We’re going to guard it. We’re going to get paid for guarding it – a lot of money,” he added.
“We’re going to be reimbursed, because the other nations are very wealthy. They’re on our side, and we can’t be expected to do that for nothing.”
Iran rejects US actions
Iran’s Islamic Revolutionary Guard Corps (IRGC) accused the United States of endangering global oil and gas supplies through its actions in the Strait of Hormuz.
IRGC spokesperson Hossein Mohebi said Washington had “seriously endangered the security of the world’s oil and gas supply and must be held accountable”, adding in a post on X that Tehran “will continue to exercise sovereignty over and management of the Strait of Hormuz”.
Meanwhile, Iran’s Khatam al-Anbiya Central Headquarters rejected any US role in managing the waterway.
According to Iran’s state broadcaster Press TV, Khatam al-Anbiya spokesperson Ebrahim Zolfghari said, “We will not allow the US to interfere in the management of the Strait of Hormuz under any circumstances.”
“The US and the countries cooperating with its military bear full responsibility for all insecurity and the escalation of the war in the region,” he added, according to the broadcaster.
Tanker traffic declines
The renewed tensions have already affected maritime traffic through the Strait of Hormuz.
Shipping data showed the number of tankers transiting the waterway fell to its lowest level in nearly two months.
Shipping industry sources told Reuters that an increasing number of vessels were switching off their Automatic Identification System (AIS) tracking transponders, making it more difficult to determine the actual volume of shipping.
Analysis by shipping intelligence firm Kpler showed that oil and gas tanker traffic had dropped to its lowest level since May 25.
Ship broker Gibson warned that any prolonged disruption to traffic through the strait could have severe consequences for global energy markets.
“Should the renewed escalation in the strait lead to another prolonged closure of Hormuz, the world will find itself in a much tougher spot,” Gibson said in a report.
“With global inventories rapidly depleted in recent months, this is a recipe for much tighter supply, higher prices and significant downside risk for tanker markets.”
IMO rejects transit fee proposal
Meanwhile, the United Nations’ International Maritime Organisation (IMO) said it opposed imposing transit fees on vessels using international straits after Trump’s proposal to levy charges on cargo passing through the Strait of Hormuz.
IMO spokesperson, cited by Reuters, said the agency was aware of Trump’s announcement and was awaiting further details.
“We are aware of the post and awaiting more details,” the spokesperson said.
“We have always been consistent on our stance on fees. IMO stands firmly against charging fees for passage through straits used for international navigation. There is no legal basis through which to introduce mandatory tolls simply to transit through a strait,” the spokesperson added.
