After talks in Pakistan between the United States and Iran broke down over the weekend, President Donald Trump ordered the US Navy to block ships entering or leaving any Iranian port or coastal facility via the Strait of Hormuz. The move is intended to deny Tehran a key source of revenue and compel it back to the negotiating table.
Prior to the conflict that began in late February, roughly one in five barrels of the world’s seaborne oil passed through Hormuz, the narrow channel linking the Persian Gulf to the Indian Ocean. If fully enforced, the blockade would stop nearly 2 million barrels per day of Iranian crude exports, cutting off the country’s primary export earnings.
US officials framed the action as removing Iranian leverage gained from controlling the waterway, which Tehran effectively sealed when the war began, stranding hundreds of tankers. President Trump also accused Iran of charging vessels up to $2 million for safe passage and said any ship paying such an illegal toll would not be guaranteed safety. He said the US Navy would begin clearing mines Iran laid in the strait.
The United States Central Command (CENTCOM) released a notice to mariners saying the blockade would not target traffic to and from non-Iranian ports like Saudi Arabia, Qatar and the United Arab Emirates. CENTCOM said the operation would be enforced in the Gulf of Oman and the Arabian Sea east of the Strait of Hormuz and would cover the entire Iranian coastline, not just ports and terminals. Any vessel entering or leaving the blockaded area without authorization, the advisory warned, could be intercepted, diverted or captured.
Maritime law specialists noted that enforcement would likely rely on the wartime right of visit and search, allowing US warships to stop and inspect tankers and divert ships suspected of carrying Iranian oil. While such actions have precedents in naval conflict, experts cautioned the blockade risks overlapping disputed maritime zones and disrupting neutral shipping lanes, potentially causing long-term harm to a vital international artery.
Within hours of the order, ship-tracking data showed tanker traffic through the strait had largely stopped. CENTCOM later reported that no vessels had passed the blockade and that six ships complied with orders to turn back to port. Trump warned Iran against any retaliation, saying remaining Iranian fast attack craft that approached the blockade would be eliminated.
The blockade could sharply limit offloading from Kharg Island, Iran’s main export terminal that handles more than 90 percent of its oil shipments. Tehran has kept exports flowing despite sanctions by using an aging shadow fleet and ship-to-ship transfers off places like Malaysia. The US previously granted Iran temporary allowances to sell oil to stabilize markets during the conflict, but the new naval interdiction makes such operations riskier because vessels face the possibility of boarding, seizure or diversion.
In 2025, Iran’s oil exports generated about $45 billion, roughly 13 percent of GDP, according to Capital Economics. With no major land pipelines for rerouting crude, Iran has limited alternatives to maritime shipments; even its Jask terminal on the Gulf of Oman could be subject to US search. Sustained pressure at sea could therefore deprive Tehran of funds and increase the political pressure to return to talks.
Iran’s Revolutionary Guard Corps responded with threats, warning that restrictions on Iranian ports would make no port in the Gulf and Sea of Oman safe and raising the prospect of strikes on energy or shipping infrastructure in the region. Ebrahim Rezaei, a spokesperson for the Iranian parliament’s National Security Commission, said Tehran was ready to respond militarily if necessary and hinted at other measures it has not yet deployed.
Some US and international analysts questioned whether the blockade is sustainable, noting it could draw the United States into a prolonged naval commitment. A former senior Pentagon official said the mission would be hard to carry out alone and difficult to sustain over the medium to long term. Economists and regional experts also suggested the move may be intended to pressure China, which has taken 80 to 90 percent of Iran’s seaborne crude in recent years, to help mediate a ceasefire and reopen the strait to trade. They warned that seizing allied or foreign-flagged ships that paid tolls could represent a significant escalation.
China’s Foreign Ministry called the blockade dangerous and irresponsible, and President Xi Jinping said Beijing was willing to play a constructive role in promoting peace in the Middle East. The episode raises the prospect of wider diplomatic and economic fallout if naval interdiction persists, with global energy markets and regional security both at stake.
Edited by: Tim Rooks