After all the tough talk, is Trump’s blockade in the Strait of Hormuz actually doing anything?

After high-stakes peace talks in Islamabad collapsed over the weekend, the future of a fragile ceasefire between the US and Iran now appears to rest on a 100-mile waterway between the Persian Gulf and Arabian Sea. The United States imposed a blockade on Iranian ports and coastal areas east of the Strait of Hormuz, which came into effect at 3pm BST on Monday. America’s Central Command warned that vessels will be subject to “interception, diversion and capture” regardless of their flag. More than 15 US warships are in place to support the operation, a senior official told the Wall Street Journal. President Donald Trump threatened that ships sailing from Iranian ports would be subject to “the same system of kill that we use against the drug dealers on boats at Sea”, referring to the administration’s controversial attacks on boats off the coast of Venezuela. Oil prices surged in response to the threats but the US military insisted that the action would “not impede” movement of ships through the Strait of Hormuz. But despite the rhetoric, a US- sanctioned Chinese tanker, the Rich Starry, appeared to sail straight through the Strait on Tuesday in apparent defiance of Trump’s blockade. A ship is seen off the coast of Ras al-Khaimah, the day after the failure of US-Iran peace talks on April 13, 2026. (AFP/Getty)What does Trump’s blockade involve?In practice Trump’s blockade will impact vessels departing from Iran’s ports and coastline, regardless of their country of origin. The US has explicitly said it will not target vessels that aren’t linked to Iran or its ports, but those that are will be intercepted, diverted or captured. However, the US leader has also ordered the Navy to hunt down vessels that have paid Iran a transit toll, which includes Chinese tankers and Indian bulk carriers that are not parties to the conflict, according to Professor Barry Appleton, co-director for for international law at New York Law School. “You have a narrow, mine-threatened strait, active hostilities, and now the US Navy is being asked to police every vessel entering or leaving Iranian ports,” he told The Independent. “That's not a blockade. It is more akin to a traffic enforcement operation in the middle of a war zone.”Trump has demanded that Iran reopen the Strait of Hormuz (Reuters)Has the blockade been working?According to marine traffic data analysed by Kpler, five liquid tankers have transited the Strait of Hormuz since the blockade was in place. For all categories—liquids, LNG, LPG, and dry bulk—a total of eight vessels crossed between 13 and 14 April.“The objective is to constrain Iran’s ability to export crude and condensate, which could eventually lead to production shut-ins.” senior crude analyst,” Johannes Rauball, told The Independent. But Tehran appears to have moved its oil offshore in anticipation of the restrictions and the volumes of its oil in transit also remains elevated, according to Kpler. This week, floating storage of Iranian crude - a method of producing and storing oil and gas on open waters away from land or ports - rose to 42 Mbbls (or 42 million barrels) up from 38 million on Sunday 12 April. Floating storage is defined as crude-carrying tankers that have remained idle and reduced their speed for at least seven days, essentially "waiting for instructions" on water. Because Iranian oil supply is exceeding demand, some tankers have been unable to discharge their load and find buyers.“While any reduction in Iranian exports would primarily impact China, which absorbs the vast majority of these flows, overall availability of Iranian crude is expected to remain ample,” explains Rauball. An aerial photo taken on April 7, 2026, shows a floating production, storage and offloading vessel (FPSO), built for Brazilian oil and gas producer Petrobras, being towed out of the dock by tugboats at a shipbuilding yard in Yantai, in China's eastern Shandong province. (AFP/Getty)“We are observing significant concentrations of floating storage near China, including roughly 15 Mbbls in the Yellow Sea and around 7 Mbbls in the South China Sea.”Rauball suggests that this could mean up to 120 days of availability of Iranian crude for China, meaning Iran is unlikely to be impacted by the blockade anytime in the near future due to “substantial volumes already on the water”. “In total, Iranian crude on water—including both floating storage and cargoes in transit—stands at approximately 190 Mbbls,” explains Rauball. “With China typically importing around 1.5 Mbd of Iranian crude, this implies roughly 120 days of cover under current conditions. “As such, even if Iranian crude exports decline, near-term availability is unlikely to tighten significantly, given the substantial volumes already on water.”Furthermore, Iran’s shadow fleet of tankers poses a further challenge to the US navy, shipping experts have warned in comments to the Wall Street Journal, allowing vessels linked to ports to transit undetected using sophisticated methods. According to Lloyd’s List, a falsely-flagged US-sanctioned tanker linked to China exited the Strait early on Tuesday. The Strait of Hormuz before Iran war and after US blockade (MarineTraffic)Chatham House analyst Neil Quilliam says it it “too early to tell” whether Trump’s blockade had been effective. “It certainly complicates the movement of vessels that Iran permits to pass through Hormuz. The passage of the Chinese tanker shows that some ship owners and their crews have a high risk tolerance and are willing to test the US - making it a test of who blinks first. It is a high stakes game.”Unmanned Underwater Vehicles (UUVs) - that can loiter underwater for up to 96 hours - can also pose a threat to billion-dollar US naval assets, according to political analyst Safi Ghauri. After nearly half a century of sanctions, further structural pressure may not hit Iran as hard as other nations, according to Ashok Kumar, associate professor of political economy at Birkbeck, University of London.“Trump’s plan to ‘blockade the blockade’ is strategically incoherent,” he says. “It’s a gesture of desperation, not strength. Iran has already moved vast quantities of oil offshore, so much of its supply simply sits beyond the reach of any naval cordon.”Transit figures reflecting tankers transporting liquid cargoes since the outbreak of war on 28 February (Kpler)Could the blockade force a confrontation?Prof Kumar says that the strategy “escalates a confrontation in one of the world’s most fragile chokepoints, where the US and global economy are far more exposed than Iran itself”. Iran has threatened to attack US partners in the Gulf if what it calls “piracy” continues.“It seems to be a tit-for-tat move by the US,” explains Quilliam. “At best, if it remains benign, then it will prevent Iran from exporting its crude, but will lead to an increase in the price of oil. In this scenario, the US aims to increase Iran’s economic pain and bring it back to the negotiating table. This move alone will not persuade the regime to reopen talks, as it has resisted sanctions for over 20 years. “At worst, Iran will challenge the blockade, leading to renewed military confrontation and include new Iranian strikes against energy infrastructure in the Gulf states, notably Saudi Arabia and export facilities in Yanbu on the Red Sea. This will lead to an even bigger hike in oil prices.”