Iranmight be outgunned and outspent by the US and Israel but it has one major advantage – its control over the Strait of Hormuz.
By attacking ships navigating the narrow waterway,Iranhas effectively shut the route, through which, one-fifth of the world's oil supply passes. And now, Tehran has also reportedly mined the strait, further deterring ships from attempting passage and marking a new escalation in the war.
Here's what you need to know:
What is Iran doing?
In recent days, Iran has begun laying a few dozen mines in the strait, according to two people familiar with US intelligence on the matter. The mining is not extensive, but Iran still maintains upward of 80% to 90% of its small boats and minelayers, one source told CNN, contradicting US President Donald Trump's claim Tehran has "no navy."
Such a move underlines Iran's reliance on asymmetric warfare and the havoc these tactics could wreak even as the country is battered by US-Israeli airstrikes.
Iran has around 5,000 to 6,000 naval mines, a report from the US Congress estimated last year. That total consists of many differenttypes of mines, the report says. Some are limpet mines, which are usually manually attached to a ship's hull by a diver; some are moored mines, which float just below the surface and explode when they come into contact with a ship; and some are "bottom" mines, which rest on the sea floor before detonating when they detect a nearby vessel.
Mines are just one part of the threat posed by Iran in the strait.
Its Revolutionary Guards, a separate force to the country's navy, is still capable of deploying a "gauntlet" of mines, explosive-laden suicide boats and shore-based missile batteries, causingone US sourceto describe the strait as "Death Valley."
That was laid bare on Tuesday when the guards said they fired on the Thai-flagged bulk carrier "Mayuree Naree" as it tried to pass through, causing an explosion in the ship's engine room. Three of the 23 crew members, who were believed to have been on duty in the engine room, remain unaccounted for, according to Thai authorities. Another Liberian-flagged vessel, named "Express Rome," was also struck by Iranian projectiles the same morning, Iran's armed forces added.
How has the US responded?
US Central Command said Tuesday it had destroyedmultiple Iranian naval ships– including 16 minelayers – near the strait, though it did not mention destroying any mines, which may have already been laid.
That followed President Donald Trump saying on Truth Social, "if Iran has put out any mines in the Hormuz Strait, and we have no reports of them doing son, we want them removed, IMMEDIATELY!"
Advertisement
If Iran didn't remove any mines it might have laid, the country would face consequences "at a level never before seen," Trump added. However, if it removed "what may have been placed, it will be a giant step in the right direction!"
American minesweeping capabilities in the Persian Gulf are not as strong as they once were. The US Navy decommissioned the last of its four dedicated minesweeper in the region last September, leaving it dependent on less specialized ships.
At the time, US Naval Forces Central Command said four littoral combat ships (LCS) would assume responsibility for minesweeping. These vessels, however, have a history of problems, leading them to be dubbed "Little Crappy Ships" by their critics.
What's at stake?
The longer the Strait of Hormuz remains impassable, the graver the implications for the global economy.
With the strait effectively closed, almost 15 million barrels per day (BPD) of crude and 4.5 million BPD of refined oil remain stranded in the gulf, according to analysts, meaning that storage tanks across the region are filling up fast.
Even in peacetime, great skill is required to navigate the Strait's narrow lane and busy traffic. The mines add to the dangers for any vessel trying to pass and make opening it up again more difficult.
Trump has proposed providing escorts for shipping in the Strait, but this would involve putting naval vessels in harm's way purely for the purpose of shielding oil ships with no obvious strategic advantage for the war itself.
While there are some other options for exporting crude via pipelines, the world's biggest oil exporter, Saudi Aramco, warned on Tuesday of the potentially "catastrophic consequences" for oil markets if flows don't resume through the strait.
Has this happened before?
Yes. During the Iran-Iraq war in the 1980s, both countries targeted each other's oil tankers in the Persian Gulf. Iran's navy laid mines close to the Strait of Hormuz, and one of these even struck a US warship – the USS Samuel B. Roberts – in April 1988.
The ship suffered substantial damage and the Reagan administration retaliated by damaging or sinking three Iranian warships and three oil platforms, drastically reducing Tehran's ability to engage in the gulf.
CNN's Natasha Bertrand, Brad Lendon, Catherine Nicholls, Tim Lister and Sophie Tanno contributed to reporting.
For more CNN news and newsletters create an account atCNN.com