Marine tracking data shows a drastic reduction in the movement of large oil tankers moving through the Strait of Hormuz, putting upward pressure on the price of crude.
US President Donald Trump has said the US Navy is prepared to start escorting oil and gas tankers through the narrow passage "as soon as possible".
Twenty per cent of the world's oil supply passes through the strait — but this visualisation of the marine traffic data shows nowhere near that amount is moving through the key body of water.
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ABC NEWS Verify obtained the tracking video via Starboard Maritime Intelligence — a ship tracking company which monitors vessels and analyses their activity.
Each marker on the map represents a single tanker of crude oil or LPG measuring over 100 meters long.
"You can see the normal traffic flow on 27 February, followed by a change in traffic patterns from 28 February," said Mark Douglas, Starboard's maritime domain analyst.
That was the day Israel and the US started attacking Iran, which led to retaliation from Iran across the region.
"[It is] getting more pronounced in the following days, until we reach March 3 and an effective halt to tankers through the Strait of Hormuz," Mr Douglas said.
"Traffic has dropped from a typical 50 tankers over 100 metres travelling in both directions every day, down to zero," he said.
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Another layer of danger can be seen in the tracking data — the "widespread" use of GPS jamming. This can be seen in markers rapidly moving between points on the map, over land or in perfectly straight lines.
"This means that, right at a time when commercial shipping is already under the threat of attack, civilian crews of these vessels have to deal with navigation systems that can't accurately tell them where the ship is," Mr Douglas said.
Some markers also appear to disappear when ships turn tracking systems off.
Iranian media reported on Monday that Iran's Revolutionary Guards commander had said the Strait of Hormuz was closed — threatening to attack any ship trying to pass through the narrow passage.
A number of tankers have been hit since war broke out — including at least one in the strait, off Oman's Masandam peninsula.
"Many tankers travelling to the Persian Gulf can be seen turning around or anchoring near the approaches to the Strait of Hormuz waiting for a safe opportunity to enter or exit the Gulf," Mr Douglas said.
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He said the reduction in traffic would also cause freight costs and war-risk insurance premiums to surge, as well as the price of fertiliser.
"A significant portion of the world's fertiliser comes from the region, and restrictions on their movement will impact farmers, and eventually consumers," he said.
