Iran Threatens Gulf Ports as U.S. Imposes Naval Blockade

A U.S. decision to impose a maritime blockade on Iranian ports has sharply escalated tensions, prompting Tehran to warn that Gulf infrastructure could become a target as ceasefire talks falter and the Strait of Hormuz remains effectively closed.

The U.S. Central Command said the blockade would begin at 10 a.m. ET (1400 GMT) on April 13, targeting vessels entering or leaving Iranian ports across the Arabian Gulf and Gulf of Oman. The move follows failed weekend negotiations in Islamabad, the highest-level talks since 1979.

Iran condemned the measure as unlawful. An Iranian military spokesperson said restrictions in international waters would amount to “piracy,” warning that “no port in the Gulf or Gulf of Oman would remain secure” if Iranian ports were threatened.

U.S. President Donald Trump defended the move, stating: “No one who pays an illegal toll will have safe passage on the high seas,” adding that any attack would be met with force.

Since the war began on Feb. 28, Iran has effectively restricted transit through the Strait of Hormuz, allowing only vessels under its control and imposing fees. The waterway carries about 20% of global energy supplies.

Oil markets reacted immediately, with benchmark prices rising more than 7% to above $100 per barrel. Physical supply constraints are more acute, with some refiners paying premiums of up to $50 above benchmark prices.

Iranian officials signaled a hardened stance following talks. Foreign Minister Abbas Araqchi said Tehran had faced “maximalism, shifting goalposts, and blockade,” adding: “Zero lessons learned. Good will begets good will. Enmity begets enmity.”

Meanwhile Iranian negotiator Mohammad Baqer Qalibaf warned of domestic impacts in the U.S., posting that Americans should “enjoy the current pump figures,” suggesting fuel prices could rise beyond $4–$5.

Energy markets face a tightening timeline. Analysts at JP Morgan noted that the last pre-closure tanker from Feb. 28 is expected to arrive around April 20, marking the depletion of earlier supply flows.

A two-week ceasefire that halted six weeks of U.S.-Israeli strikes is now under pressure, with only about one week remaining. Despite U.S. claims of progress, key objectives - including curbing Iran’s missile and nuclear capabilities - remain unmet.

Iran retains a stockpile of more than 400 kg (900 pounds) of highly enriched uranium, according to U.N. estimates, alongside missile and drone capabilities targeting regional states.

U.S. officials said Iran rejected demands to abandon uranium enrichment and halt regional support networks, while Tehran insisted on sanctions relief and recognition of its authority over Hormuz.