US military will target Iran-linked ships worldwide, broadening scope beyond blockade

U.S. forces in other areas of responsibility "will actively pursue any Iranian-flagged vessel or any vessel attempting to provide material support to Iran," he told reporters at the Pentagon.

The military also detailed an expansive lists of goods that it considers contraband, declaring that it will board, search and seize them from merchant vessels "regardless of location." A notice published Thursday says any "goods that are destined for an enemy and that may be susceptible to use in armed conflict" are "subject to capture at any place beyond neutral territory."

The expansion of U.S. military efforts to target Iranian shipping is another pressure point for Tehran and comes as a ceasefire is set to expire in mere days. Mediators are pressing for an extension to a truce that has paused almost seven weeks of war between Israel, the U.S. and Iran.

Military details items that could be seized from ships

The military's new list of banned materials includes products such as weapons, ammunition and military equipment that are classified as "absolute contraband." However, it also lists items such as oil, iron, steel, aluminum and other goods as "conditional contraband" that it argues can be used both for civilian and military purposes.

Otherwise innocuous items like electronics, power generation equipment or heavy machinery can be seized if "circumstances indicate intended military end-use," the notice says.

More than 10,000 American troops are helping enforce the blockade on Iranian ports. While no ships have yet been boarded, defense leaders say the military is warning Iran-linked ships that it could fire warning shots or escalate to other force if they try to outrun the Navy.

In the first three days of the military action, 14 ships have turned around rather than confront the naval blockade, according to U.S. Central Command, which oversees the Iran war.

Some Iran-linked or sanctioned vessels that have left the Persian Gulf through strait have appeared to halt their movements, turn off their radio transponders or head back toward Iran's coast, shipping data firms say.

U.S. military warns ships near the blockade

Vessels that approach the blockade, which is being enforced in Iran's territorial seas and international waters and not in the Strait of Hormuz, are given a warning, Caine said.

"Any ship that would cross the blockade would result in our sailors executing pre-planned tactics designed to bring the force to that ship — if need be, board the ship and take her over," he said.

U.S. Central Command released a recording of a radio broadcast sent to vessels in the region that said the military was ready to use force if needed to compel compliance with the blockade.

"Vessels will be boarded for interdiction and seizure transiting to or from Iranian port," the message said.

Defense Secretary Pete Hegseth told reporters that "less than 10% of America's naval power" is being used to enforce the blockade. The Navy has 16 warships — 11 destroyers, three amphibious assault ships, an aircraft carrier, and a littoral combat ship — in the Middle East out of a battle force of roughly 300 total warships.

Also supporting the blockade is a series of aircraft as well as surveillance, reconnaissance and intelligence operations designed to give the Navy the latest information on the vessels it is encountering.

Caine noted the congestion of the area around the blockade, likening it to a crowded parking lot and U.S. destroyers to high-powered sports cars.

"There is a lot out there," Caine said. "It is like driving a sports car through a supermarket parking lot on a payday weekend, with thousands of kids in that parking lot, as you attempt to maneuver through there to get to that ship that would attempt to run that blockade."

U.S. Central Command chief appears at the Pentagon

As Hegseth and Caine discussed the blockade, Adm. Brad Cooper, the head of U.S. Central Command, made a rare appearance in the Pentagon briefing room.

He said that before the ceasefire took hold, American service members and troops from allied countries in the Persian Gulf had "fought together side by side."

"In creating the largest air defense umbrella in the world across the Middle East, we embedded specially trained U.S. military air defenders alongside our partner nation soldiers," Cooper said, adding that Bahrain's king and crown prince knew American soldiers by name.