On 13 April 2026, at 10 a.m. ET, the U.S. military naval blockade of Iran took effect, at the direction of Donald Trump and under the command of Admiral
Brad Cooper at the United States Central Command. According to CENTCOM, the blockade is set to encompass "the entirety of the Iranian coastline," warning that any vessel "entering or departing the blockaded area without authorization is subject to interception, diversion, and capture." President Trump threatened to strike any fast-attack ships of the
IRGC Navy with drug boat-style attacks, similar to those
carried out against alleged drug traffickers in the
Caribbean Sea during
Operation Southern Spear. In the first 24 hours after the blockade took effect on 13 April 2026, CENTCOM reported that over 10,000 U.S. personnel, supported by more than a dozen warships and dozens of aircraft, were enforcing the operation. No vessels attempted to breach the blockade, while six commercial ships complied with orders and were redirected back to Iranian ports. CENTCOM added that "The blockade will be enforced impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including all Iranian ports on the
Arabian Gulf and
Gulf of Oman. CENTCOM forces will not impede freedom of navigation for vessels transiting the Strait of Hormuz to and from non-Iranian ports." On 14 April, at least four ships related to Iran crossed the Strait of Hormuz, according to public transponder data viewed by
BBC Verify. Those vessels later stopped or turned around, after presumed interception by US forces, according to shipping data firms and the
Sydney Morning Herald. On the same day, a US official stated that a total of 8 oil tankers entering or leaving Iranian ports had been intercepted since the start of the blockade. All tankers complied with directions to reverse course and no boarding was necessary. Tankers departing from the
Chabahar Port were contacted by a US
destroyer, while
Boeing P-8 Poseidon patrol aircraft were also used to intercept tankers. On 16 April,
Chairman of the Joint Chiefs of Staff, General
Dan Caine, held a press conference with Secretary of Defense
Pete Hegseth. They clarified that the blockade is on the ports and coastline of Iran rather than the Strait of Hormuz, and that enforcement will also occur in other areas. It was announced that the
United States Indo-Pacific Command under Admiral
Samuel Paparo would begin conducting interdiction activities against ships that left Iran before the blockade. They also stated that the number of vessels intercepted by US forces had risen to 13, but all so far had complied with US directions. On 19 April, the US seized the Iran-flagged cargo ship after it attempted to breach the blockade. The vessel, almost long, was en route to Bandar Abbas. It was warned by the guided missile destroyer over a six-hour period before the destroyer fired several rounds from its
5-inch/54-caliber Mark 45 gun into the engine room, disabling it. It was then seized by the
31st Marine Expeditionary Unit in the Gulf of Oman. Iran retaliated against the seizure by launching attack drones at U.S. ships, although no damage was reported. According to Reuters, the seized ship was probably carrying equipment that the US considered "dual-use," meaning that it had equipment that could be used by the Iranian army. On 20 April, it was reported by
Lloyd's List that at least 26 Iranian ships had successfully bypassed the American blockade, including 11 tankers with Iranian cargo that managed to exit the Gulf of Oman. On the same day, CENTCOM announced that the number of intercepted ships had risen to 27. Overnight on 21 April, US forces boarded the stateless oil tanker MT
Tifani in the
INDOPACOM operational region, stating that it was linked to Iranian smuggling. The vessel had loaded oil from
Kharg Island earlier in the month but left before the blockade. On 22 April, the US said that it had intercepted a total of 29 ships. By 1 May, the US had forced 45 commercial vessels to turn around or return to port, according to CENTCOM. == Reactions ==