(Bloomberg) -- Iran has been moving its crude through the Strait of Hormuz at rates broadly comparable to transit before the war began, making the most of its control of the vital waterway as other exporters falter.

Iranian crude exports through the corridor accounts for nearly three-quarters of the 27.2 million barrels that have left the Persian Gulf since March 1, data from intelligence firm Kpler Ltd. show. That amounts to about 1.2 million barrels a day of crude for Tehran, compared to a pre-war daily level of 1.5 million barrels.

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By contrast, nearly three weeks into the war, cargoes from others in the region added up to just 400,000 barrels a day, versus an average 14 million barrels per day in peace time.

Pre-war assessments of the risk of a Hormuz closure — all but unprecedented — tended to assume that Iran would avoid extreme measures, largely because of the risk to its own exports. Asymmetric flows over the past weeks, however, show that Tehran has been able to shield its cargoes while constraining those belonging to other exporters — a chokehold that is pushing energy prices higher and forcing the US to consider increasingly muscular options to reopen the waterway.

Among other moves, the Pentagon has begun targeting missile sites near Hormuz. US President Donald Trump has called on allies for help securing the area.

“The blockade is now the worst disruption to oil flows ever,” said Muyu Xu, senior crude oil analyst at Kpler. “Real barrels are now disappearing from global oil markets, which can lead to demand destruction in the weeks to come.”

In the first week of the war, Iran-linked carriers accounted for 35% of the 20 crude tankers that made outbound transits, according to ship-tracking data from Kpler. One week later, that proportion rose to five out of the eight that left the region, as Iran’s control of shipping through the strait increased.

Crude loadings at Iran’s Kharg Island also appear to continue undisturbed, despite US strikes on the export hub. Three vessels were seen docked at the island on Tuesday, Sentinel Hub satellite images show, while two were seen on March 7. It’s unclear whether Iran had continued to load in the intervening days as there were no new images published during this period.

Oil flows through the strait have now stabilized at a fraction of their original levels, or around 500,000 barrels per day on a four-day average basis, Goldman Sachs analysts said in note on Tuesday. Compared to the pre-war average, that marks a 98% drop in volumes, or a loss of 19.5 million barrels per day.

Other Persian Gulf producers have been scrambling to find alternative routes, hoping to avoid costly shut-ins. Iraq, which began closing production in the early days of the war, agreed with regional Kurdish authorities to resume exports via Turkey. Saudi Arabia is redirecting some of its flows to the Red Sea port of Yanbu, while the United Arab Emirates is tapping Fujairah on the Gulf of Oman for exports.

These workarounds have helped narrowed the loss in oil flows from the region from 17 million barrels per day on a four-day average earlier this week to 14.9 million barrels per day on Tuesday, according to Goldman Sachs.

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