Six weeks into the war with Iran, President Donald Trump has given the US Navy the most difficult mission of the conflict: blockading Iranian ports and clearing Iranian mines from the strategic Strait of Hormuz.
The blockade order will apply from 10 a.m. ET on Monday to all Iranian ports, both inside and outside the strait, a key transit point for global energy trade that Iran has blocked since the outbreak of the war, U.S. Central Command (CENTCOM) said.
President Trump suggested the scope of the mission would be broader, perhaps extending far beyond the Persian Gulf.
“I have also directed the Navy to search and interdict all ships in international waters that have paid tolls to Iran. Anyone who has paid illegal tolls cannot safely navigate the high seas,” he said on Sunday, referring to the Iranian government’s move to charge safe passage fees to ships.
The point of this mission is to squeeze cash flows from energy trade to maximize pressure on Iran. But resolving the global energy crisis caused by this war will require another difficult task: clearing the mines laid by Iran.
President Trump said Saturday that the Navy had begun minesweeping operations in the strait. Centcom confirmed this and said two US guided missile destroyers had entered the strait to begin “setting conditions for mine clearance.”
This mission marks the transition of this conflict from the air to the sea. The conflict so far has been fought primarily by air, but early in the war a U.S. submarine sank an Iranian frigate off the coast of Sri Lanka.
Navy planes flying from aircraft carriers are also involved.
But those missions aren’t as complex or dangerous as what President Trump now wants the Navy to do.
Let’s see what’s involved here.
Blockades are a means of economic warfare as well as kinetic warfare.
The Newport Manual of Naval Law defines blockade as “the capture of contraband and the capture or destruction of enemy property found at sea.”
“These methods deprive the enemy of the potential for economic revenue from exports and the profits from imports that support the war effort,” the manual says.
To be legal, imposing a lockdown must follow certain rules, including:
This must be declared and notified, and potentially affected vessels must be warned.
It must be effective, which means the United States must have the ships and aircraft to enforce it.
It has to be fair and affects ships of any country.
Although civilians cannot be targeted exclusively, harm to civilians is acceptable.
It must not impede access to neutral ports, and it must not block straits like the Strait of Hormuz, which President Trump has said is open to international vessels not connected to Iran.
Karl Schuster, a former U.S. Navy captain and analyst, said blocking Iranian ports, nearly all of which are in the Strait of Hormuz, to oil tankers and other commercial vessels would be “procedurally difficult, but practical if the United States has maritime superiority.”
And maybe not.
Analysts say Iran still has the ability to strike back with an unknown number of small boats carrying mines, missiles, surface drones, airborne drones, small boats that can carry land-based cruise missiles, and shoulder-launched anti-aircraft missiles that can target helicopters and fighter jets protecting ships on the water.
Yoo Ji-hoon, a researcher at the Korea Institute for Defense Analysis and a former South Korean submarine officer, said a blockade is “high risk” because Iran has the option of counterattacking.
“If Iran recognizes this as a violation of its sovereignty or an expansion of a de facto naval war, the possibility of a localized military conflict may increase,” Yu said.
Retired U.S. Navy Adm. James Stavridis told CNN’s Fareed Zakaria that the Pentagon believes it would need two carrier strike groups and about a dozen surface ships outside the Gulf to patrol the Strait of Hormuz at its entrance.
Stavridis said at least six U.S. destroyers would be needed in the Gulf, as well as naval support from U.S. partner countries such as the United Arab Emirates and Saudi Arabia.
“We need to try to contain both sides,” he said of the strait.
Schuster said the U.S. Navy is training crew teams of about 10 to 14 people to operate commercial ships. Each team includes a “deck officer” who basically acts as the captain of a merchant ship after hijacking it and “guides the merchant ship to an anchorage or port for berthing.”
However, all of them take time.
Schuster said two of the six U.S. destroyers in the strait will be used to board ships, and the remaining four will be nearby to respond to Iranian attempts to prevent such actions.
The two destroyers could seize six ships a day, Schuster said.
Before the U.S. and Israel’s war against Iran, about 130 ships passed through the strait each day, and about a fifth of the world’s oil and gas flowed through it.
Jennifer Parker, a non-resident researcher at the Lowy Institute and a former Australian naval officer, said the seize approach was the more likely option if the US sought to block Iranian shipping.
Mr Parker said this fell under international “prize law”.
According to Newport’s manual, “belligerents at sea” can seize enemy merchant vessels and supplies outside neutral waters. It can also visit, search, divert or seize “neutral” commercial ships “if they are carrying contraband.”
The Bounty Act also states that neutral merchant ships can be attacked anywhere for military purposes if it “effectively contributes to the military action or combat of the enemy.”
Therefore, what we are likely to see is not a blockade (as stated), but selective interference with shipping under the Prize Act to influence shipping routes, reduce Iranian control, and create economic leverage,” Parker wrote in X.
Historically, blockades have been carried out close to a country’s coast, but modern intelligence, search and reconnaissance have made long-range operations possible, said Alessio Patalano, professor of war and strategy at King’s College London.
He said it is possible to launch operations far from Iran and then move closer if the situation requires.
This would prevent Iran from immediately exploiting the advantages of small vessels and short-range weapons, he added.
mines and minesweeping
Shortly after the war began, two people familiar with the U.S. intelligence community told CNN that Iran began planting a small number of mines in the Strait of Hormuz.
Two U.S. destroyers, the USS Michael Murphy and the USS Frank E. Peterson, passed through the strait over the weekend, but Schuster said they are unlikely to actually clear mines and are not the best platforms for mine-clearing operations.
He said the destroyer likely passed through the strait to demonstrate that such a passage was possible and that there were no mines there.
The actual mine-sweeping operations will likely be carried out by underwater drones, littoral combat ships equipped with mine countermeasures packages, and helicopters, Schuster said.
He said sea mines come in many forms, and some can go undetected or unlaunched by U.S. warships.
Things that Iran could deploy in the Strait include:
Spiked contact mines like those seen in World War II movies.
Affects mines caused by static electricity generated when a ship moves through salt water.
Magnetic mines that react to changes in the “magnetic properties” of water as ships pass by.
Acoustic mines that react to the noise made by passing ships.
A pressure mine explodes when the water pressure changes from the type of ship it is designed to destroy to the amount the mine measures.
Some complex landmines contain combinations of the above types, making them especially difficult to counter, Schuster said.
Also, some advanced mines are equipped with counters that allow them to pass a certain number of ships before detonating.
“These mines make it very difficult to determine whether all the mines in a minefield have exploded or been neutralized,” he said.
Schuster said landmines can be countered in two important ways: sweeps and hunting.
In the case of moored mines, minesweeping uses a mechanism that cuts the cables that connect the mine to the ocean floor. The mine then floats to the surface, where it can be destroyed.
In the case of bottom mines, it is a ship’s towing device that mimics the acoustic, electrical, and magnetic signature of a minesweeper and can be safely detonated.
But Schuster said minesweeping techniques don’t work against complex, high-pressure mines.
They are detected and safely destroyed by underwater drone sonar and lasers mounted on drones and helicopters.
Analysts also point out that there are limits to U.S. minesweeping capabilities alone.
Last year, the US Navy retired four special minesweepers based in Bahrain in the Persian Gulf.
The minesweeping mission was taken over by three littoral combat ships equipped with mine countermeasures packages, but their locations were not disclosed. Two of them were spotted in Singapore last month.
Analysts said the U.S. government may need to look beyond its home base to thoroughly clear the Strait of Hormuz of sea mines.
“This is an area where the U.S. Navy will probably rely on its allies and partners more than expected,” Patalano said.
