President Donald Trump extended a waiver of the Jones Act for an additional 90 days on Friday, aiming to curb rising U.S. energy costs caused by the ongoing war in Iran.

The Jones Act, formally the Merchant Marine Act of 1920, mandates that goods transported between U.S. ports must be carried on American-built, owned, flagged, and crewed vessels. Waivers allow foreign-flagged ships to participate during emergencies or national defense needs.

Trump first waived the law on March 18 for 60 days after the conflict with Iran severed one-fifth of global oil supplies, particularly through the Strait of Hormuz, driving up domestic fuel prices. The initial waiver expires May 17, and the new extension runs through mid-August, covering shipments of oil, fuel, and fertilizer.

White House Press Secretary Taylor Rogers stated on X that the move begins at midnight ET on May 18 and provides 'certainty and stability for the U.S. and global economies.' She noted new data showing the original waiver enabled over 40 tankers to transport more than 9 million barrels of oil between U.S. ports, boosting capacity by 70 percent and speeding deliveries.

Administration officials highlighted benefits in regions like Alaska, where waiver shipments met half the state's average monthly jet fuel needs. The extension responds to persistent supply chain issues and elevated shipping costs from the Iran conflict, now in its second month.

Trump has linked the waiver to broader efforts, including releasing 172 million barrels from the Strategic Petroleum Reserve and easing sanctions on Russian oil. He predicted crude and gasoline prices would fall once the war subsides.

Supporters, including analysts at the Cato Institute, praised the policy for expanding shipping options and reducing costs without harming national security. Critics from the American Maritime Partnership argued the waiver undermines U.S. shipbuilders, unions, and military readiness by favoring foreign carriers. Jennifer Carpenter, the group's president, called it 'an affront to hundreds of thousands of hardworking Americans' and a sabotage of Trump's maritime agenda.

The decision comes ahead of midterm elections, where fuel prices remain a political flashpoint. Energy producers and refiners have long sought Jones Act reforms to lower costs, while domestic maritime interests defend it as vital for jobs and defense logistics.