‘Turn Around or Prepare to Be Boarded,' US Warns Ships
Senior U.S. defense officials on Thursday used a Pentagon press conference to describe how American forces are enforcing the naval blockade of Iranian ports, including the warnings issued directly to shipmasters approaching restricted waters.
Defense Secretary Pete Hegseth, Joint Chiefs Chairman Dan Caine and U.S. Central Command commander General Brad Cooper said U.S. warships are repeatedly instructing vessels to turn around if they attempt to travel to or from Iranian ports, with Caine outlining the language used over open radio channels.
The update comes as the war with Iran continues to disrupt global shipping and energy flows, with many ships and seafarers stranded in the Persian Gulf amid uncertainty over whether diplomacy can ease passage through the Strait of Hormuz.
Why It Matters
The naval blockade of Iranian ports remains one of Washington's most consequential tools in a conflict that has already produced what energy analysts describe as the largest disruption of global oil and gas supplies on record. About 20 percent of the world's oil and liquefied natural gas normally transits the Strait of Hormuz, making prolonged restrictions a global economic concern.
For commercial shipping, the procedures described Thursday underline that enforcement is active and physical, not symbolic. Vessels attempting to challenge the blockade face boarding and seizure, influencing insurance premiums, rerouting decisions and the willingness of crews to enter the region.
What to Know
Thursday's briefing offered the clearest public explanation yet of how the blockade is being carried out on the water.
Caine centered his remarks on the enforcement process, offering a detailed account of the radio warnings delivered to ships. He described a junior officer on the bridge of a U.S. destroyer transmitting a standardized message.
"A junior officer picks up that mic and transmits, and I quote, ‘Do not attempt to breach the blockade. Vessels will be boarded for interdiction and seizure, transiting to or from Iranian ports. Turn around or prepare to be boarded. If you do not comply with this blockade, we will use force,'" Caine said.
Caine emphasized that the warning is reinforced by the physical presence of U.S. naval forces. As the message is broadcast, he said, shipmasters can "literally see, sense and feel the pressure around them" as American warships maneuver nearby. He described the operation as a "finely tuned machine."
According to Caine, the warning-and-turnaround sequence has been executed 13 times since the blockade began Monday, with vessels choosing to reverse course rather than proceed.
Cooper stressed that the blockade is narrowly focused on traffic tied to Iranian ports, not an attempt to close the Strait of Hormuz altogether.
The military update came as new reporting highlighted possible diplomatic maneuvering by Tehran. A Reuters report published Wednesday said a source briefed by Iranian officials indicated Iran could consider allowing ships to sail freely through the Omani side of the Strait of Hormuz without risk of attack, if a deal is reached with Washington to prevent renewed conflict.
Reuters reported that the war with Iran has produced the largest-ever disruption of global oil and gas supplies because of Iran's interruption of Hormuz traffic. Since fighting began on February 28, hundreds of tankers and other vessels, along with thousands of seafarers, have been stuck inside the Gulf.
However, major uncertainties remain. The source did not say whether Iran would clear any underwater mines it may have placed in the area, or whether all ships-including those linked to Israel-would be allowed to pass freely. Reuters said the source emphasized that any safe‑passage arrangement would hinge on whether Washington is prepared to meet Tehran's broader demands, a factor described as central to any breakthrough.
What Happens Next
With the ceasefire scheduled to end next week, the direction of the conflict-and the rules governing shipping near Iran-will hinge on whether talks yield an extension or hostilities resume.
Newsweek's reporters and editors used Martyn, our Al assistant, to help produce this story. Learn more about Martyn.
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This story was originally published April 16, 2026 at 11:06 AM.