Iran’s fortifications on small islands near the Strait of Hormuz boost its power to control the key waterway, and reopening shipping there might require U.S. or allied forces to capture some of those same dots of land.
The importance of the islands such as Kharg, Qeshm and Abu Musa is increasingly coming into view as Iran causes an economic crisis by blocking most oil tankers from transiting the strait. The waterway carried about 20% of the world’s traded crude oil before the war; traffic has slowed to a trickle since the U.S.-Israeli air war on Iran began on Feb. 28.
“Navigation through the Hormuz Strait requires you to follow a certain route,” says Yossi Kuperwasser, former head of Israeli military intelligence research and now director of think tank Jerusalem Institute for Strategy and Security. “This route goes between islands that are controlled by Iran.”
Tehran has called its 19 islands in the 100-mile strait aircraft carriers, installing radar systems, airstrips and fuel depots, missile systems and naval launches for submarines and fast-attack boats.
Unlocking the strait promises to be the next phase of the war, either through a negotiated peace agreement or a military operation. An amphibious assault ship, the USS Tripoli, arrived in the Middle East over the weekend ferrying elements of the 31st Marine Expeditionary Unit, which is specifically trained for operations such as taking control of islands in hostile territory.
Iran’s most strategically important island, Kharg, is actually hundreds of miles northwest of the strait itself. Iran loads 90% of its crude oil at Kharg, making it the beating heart of Iran’s economy.
The U.S. launched a furious aircraft-and-missile assault on Kharg focused on eliminating its military installations. But the attack didn’t touch the oil facilities, and market analysts said tankers continued to load at Kharg in the following days.
President Trump has repeatedly spoken of seizing Kharg as leverage to compel the regime to lay off Hormuz. But taking Kharg would be difficult because it is large and located deep in Iranian territory. And there is no guarantee American control of Kharg’s oil facilities would force Iran’s hand.
The largest island at the Hormuz Strait, Qeshm is critical for Iran’s control of Hormuz. Another location for oil exports, Qeshm hosts a naval station and missiles in underground tunnels. It is also the site of a large desalination plant that Tehran has accused the U.S. of bombing.
Smaller islands near Qeshm are likewise fortified with military structures, including Hormuz to the east. Kish, westward into the Gulf, has an airstrip.
Perhaps most directly tied to Hormuz transits, Larak is linked to Iran’s monitoring of vessel traffic and a key military asset for the regime.
Outwardly a barren desert island, Larak has housed a Russian-made satellite communications-jamming system guarded by Iranian naval infantry and fast-attack vessels with antiship missiles, according to Israel-based Alma Research and Education Center.
As Iran has asserted new levels of control over the strait since the war began, Larak has been used by the Islamic Revolutionary Guard Corps to monitor ship traffic, said Max Meizlish, a research fellow at the Foundation for Defense of Democracies and a former sanctions enforcement officer in the U.S. Treasury’s Office of Foreign Assets Control. Meizlish described Larak as “the corridor’s operational backbone.”
In the past, ships transiting the strait passed closer to its southern side, nearer the coast of Oman. But as Iran exerts gatekeeping power, analysts at Lloyd’s List Intelligence say vessels are now transiting a channel between Larak and Qeshm, and hugging the Iranian coast as they head to open seas. Nearly all of the tankers that have exited Hormuz since the beginning of the war have had an Iran connection, according to Lloyd’s.
“This is not how things were moving prior to the war, and it’s a really disturbing development in terms of Iran exerting control over traffic through the Straits,” Tomer Raanan, a Lloyd’s maritime-risk analyst, told an online conference last week.
Raanan said Iran appears to be putting in place a screening system where vessel operators need to contact the IRGC, the powerful paramilitary force running the war effort, through an intermediary and provide documentation to get clearance. In a small number of cases, ships have paid to transit, with the going rate quoted at up to $2 million in Chinese yuan for a very large crude carrier, Raanan said.
Abu Musa is where Iran locked in control over the strait 55 years ago. Closer to Dubai than to the Iranian mainland, Abu Musa was a British protectorate along with seven emirates that are today the United Arab Emirates.
In 1971, the U.S.-backed Shah of Iran put troops on Abu Musa along with Greater Tunb and Lesser Tunb during a period of turmoil sparked by British retreat from the region. The Emiratis sustain claims to the islands today.
A pair of tiny sun-baked islands called Greater Tunb and Lesser Tunb are Iran’s eyes on the channel, and of course have boasted military fortifications. The larger of the two, Greater Tunb, is about 4 square miles, about the size of Key West.
It is here where Iran has territory closest to the shipping lanes. The strait itself is roughly 21 miles wide at its narrowest point, but ships actually track along two deep channels—one westward into the Gulf and one out—that are each only about 2 miles wide. The Tunb islands sit in between the two channels.
Write to James T. Areddy at James.Areddy@wsj.com, Roque Ruiz at roque.ruizgonzalez@wsj.com and Max Rust at max.rust@wsj.com