Oil tankers are beginning to avoid the Strait of Hormuz as the United States moves closer to enforcing a naval blockade, following the collapse of peace talks with Iran.
Shipping data shows vessels are already changing course ahead of the planned operation, which is expected to begin later on Monday.
President Donald Trump announced the move after negotiations with Iran failed to produce a deal, putting a fragile two-week ceasefire at risk and raising fresh concerns about global oil supply.
According to the U.S. Central Command, the blockade will target ships heading to or from Iranian ports.
It is set to take effect at 10 a.m. ET (1400 GMT) and will apply to vessels of all nationalities operating in Iranian coastal waters.
However, U.S. officials say ships passing through the Strait of Hormuz to non-Iranian destinations will still be allowed to move freely, suggesting the aim is to isolate Iran rather than shut down the entire route.
Even so, the tension is already affecting shipping behaviour.
A Malta-flagged supertanker that attempted to pass through the strait on Sunday reportedly turned back and is now anchored near the Gulf of Oman.
It had been heading into the Gulf to pick up crude oil before reversing course.
At the same time, two Pakistan-flagged tankers entered the Gulf without incident and are expected to load cargo in the United Arab Emirates and Kuwait.
Another large crude carrier also made it through earlier in the day and is now operating within the Gulf.
Iran’s Revolutionary Guard has warned that any military vessels approaching the strait would be seen as violating the ceasefire and would be met with a strong response.
Despite the rising tension, some oil shipments are still getting through. Data shows that three fully loaded supertankers managed to pass through the strait on Saturday the first to exit the Gulf since the ceasefire was announced last week.
With uncertainty growing and military threats on both sides, shipping companies appear to be taking a cautious approach, avoiding unnecessary risks in one of the world’s most critical oil routes.
