President Trump said Wednesday that the U.S. has total control of the Strait of Hormuz. The reality on the water tells a different story.
Ship-tracking data shows just 14 vessels on Tuesday crossed a waterway that routinely handled more than 130 a day before the war. Eleven of those ships took the route administered by Iran. Traffic was slow throughout July, with an average of 26 crossings a day, and in June, with 33 a day, as renewed Iranian attacks on ships cut short a deal to open the strait.
The disconnect shows how Tehran has managed to squelch traffic through the crucial energy chokepoint with relatively little military force, only a handful of drone and missile attacks on ships. Iran doesn’t need to defeat the U.S. Navy. It just needs shipping companies, captains and insurers to believe ignoring its dictates could get a ship hit.
“Iran is using the fear factor of real physical risk to retain a measure of control,” said Rachel Ziemba, an adjunct senior fellow at the Center for a New American Security, a Washington think tank. “The risk-reward is simply not there for many global tankers.”
Trump pushed back Wednesday on social media, saying Iran has no way to force its will on the waterway with its armed forces decimated by the war and the country struggling with a spiraling economy.
“The U.S.A. has total control over the Strait of Hormuz. I THINK WE WILL KEEP IT!,” the president said, “and there is nothing Iran can do about it.” He ended the post saying, “Praise be to Allah!”
While the U.S. Navy has guided a number of tankers through the strait, taking some pressure off energy markets, it remains an effort around the margins. Iran’s grip on the strait has cost the world more than 2.6 billion barrels of oil since the U.S. and Israel launched the war in February, Saudi Aramco Chief Executive Amin Nasser said last week.
Iran’s attacks have deterred captains from using the route along the Omani coast protected by the Navy. According to ship tracking firm Kpler, around half of the ships that risked crossing the strait in August chose the route administered by Iran. The other half chose to go dark when crossing, meaning their location beacons were off and their routes aren’t known. Only two out of the 166 crossings used the U.S.-backed route along Oman.
“The southern Omani corridor cannot presently be considered a reliably protected transit route,” said Dimitris Maniatis, founder and CEO of maritime-risk company Marisks.
The International Energy Agency said Wednesday the Strait of Hormuz has been effectively closed again since June’s deal to open the waterway collapsed last month. The renewed disruptions have derailed a nascent recovery in oil supplies from the Gulf.
Last week, Trump said that the U.S. blockade on Iranian ports meant the Strait of Hormuz was “sort of open right now,” though he acknowledged Tehran could still damage ships with missiles, drones and mines.
Continued disruption of oil and gas flows threatens to push energy and shipping costs higher, rekindle inflation and weigh on global growth. For Trump, it also risks turning a distant war—already over five-months long—into a domestic liability through higher gasoline and consumer prices just months before the midterm elections.
Control of the strait, which before the war carried about a fifth of the world’s oil, has become the main sticking point in talks to de-escalate tensions with Iran. Trump imposed a naval blockade on Iran in April, then lifted it under his June deal to reopen the strait and begin winding down the war.
That ceasefire unraveled in early July after Iran targeted commercial ships around Hormuz and Washington accused Tehran of violating the deal. Trump resumed strikes and withdrew sanctions relief, while Iran again enforced its preferred shipping routes, effectively ending the truce.
Iran’s attacks have been sporadic. The United Arab Emirates said Iran struck one of its ships on Saturday, following hits on three others last week. Iran hasn’t attacked commercial vessels since the weekend.
The uncertainty is a powerful deterrent. Iran doesn’t have to sink ships to control traffic—the perceived possibility of an attack can make a single voyage cost millions more to insure.
After easing following the June ceasefire, war-risk insurance for a Hormuz transit has risen to as much as 10% of a ship’s value, according to insurance broker Marsh. It was roughly 0.25% before the war. That could mean $3 million to $10 million in insurance costs for a single large tanker to transit, Marsh said.
While attacks at the Strait of Hormuz have abated for now, those at the Bab al-Mandeb Strait on the Red Sea have turned deadly. Yemen’s Iran-backed Houthi rebels have widened the scope of the war by attacking ships there.
The Houthis struck the Tanzanian-flagged cargo ship Tihamah off Yemen on Tuesday, killing four sailors, according to Yemeni authorities. The ship was hit again as rescuers arrived to evacuate the crew.
The deaths were the first linked to Houthi attacks on shipping since the U.S.-Iran war began, according to MarineTraffic.
Seafarers on ships stuck in the Strait of Hormuz still receive frequent warnings from Iran’s Islamic Revolutionary Guard Corps navy on marine radio, telling them to ask for permission before crossing. Meanwhile, those on vessels anchored near Oman occasionally hear the U.S. Navy warning vessels trying to run the blockade and exit the Persian Gulf to return to their last port of call.
U.S. forces fired on a Panama-flagged cargo ship early Tuesday after it attempted to run the blockade. The crew ignored warnings to turn back, the U.S. military said.
Write to Rebecca Feng at rebecca.feng@wsj.com and Georgi Kantchev at georgi.kantchev@wsj.com