Roland Oliphant
As the Strait of Hormuz crisis deepens, lifting the Iranian blockade has become Donald Trump’s central war aim. For strategists at the Pentagon, that may come as a relief.
Unlike some of the US president’s original stated reasons for going to war, reopening the Strait is a matter of necessity rather than choice. It is also a better-defined and achievable goal than his initial, sometimes vague, objectives.
No one imagines it will be easy, but if any military in the world is up to the task, it is America’s. Success – thwarting Iran’s attempt to hold the world’s economy hostage – would give Trump a victory that would allow him to end the war.
So, how can it be done?
Air strikes all along the coast, the sinking of the Iranian surface fleet and threats to destroy Iran’s energy grid have all, so far, failed to reopen the vital waterway through which a fifth of all oil and gas supplies flow in peacetime. Diplomatic overtures are also yet to bear fruit.
Signalling his intent to break the deadlock – by force, if necessary – Trump has dispatched two amphibious assault groups to the region.
The 31st Marine Expeditionary Unit (MEU), usually based in Okinawa, is expected to arrive in the Middle East by the weekend, followed by the 11th MEU dispatched out of the Marine Corps Base Camp Pendleton in California, which is set to reach the region by mid-April.
Each comprises several ships carrying around 2500 marines, along with Osprey tilt-rotor helicopters, landing craft, and other equipment required for amphibious and airborne assaults.
Each is also designed to put ashore, if ordered, battalion combat teams of 1200 to 1500 troops and to keep them fighting for 30 days without resupply.
‘We know how to open the Strait. It’s just very expensive and difficult.’
Peter Mansoor, professor of military history, Ohio State University
And it is not only the marines. On Wednesday (Washington time), the Pentagon ordered up to 3000 paratroopers from the 82nd Airborne Division to deploy into the region.
And these are only the movements the White House has announced. Other spearhead units, including specialist engineers and special operations forces, such as the 75th Ranger Regiment, could also be called on.
Together, they provide Trump with multiple options for taking the war from the air and sea to the ground. But how will he choose to use them?
‘Distract, deter, deceive’
The first doctrinal role of the marines is not necessarily to fight, but to threaten to.
Moving up and down a coastline to “distract, deter or deceive” the enemy is one of the prime operational uses of amphibious forces, says Vice Admiral Andrew Burns, a former commander of the Royal Navy’s amphibious task group.
In other words, just because the Marines are on the way to the region does not mean they will land on Iranian shores. If they do, however, the stakes will rise precipitously.
“When they’re on ships, the ability to land the Marines anywhere keeps the enemy guessing. That’s at the operational level of war. But when you land them, it becomes a tactical problem, and a very high-risk tactical problem,” says Andrew Milburn, a retired US Marines colonel. “You have to decide whether the reward is worth all that risk.”
If their boots do touch dry land, it is likely to be on one of the roughly half-dozen islands dotted around the Strait of Hormuz.
“The Iranians have fortified those islands over the last three or four decades,” Milburn says.
“They’ve got infrastructure there that could support operations to disrupt shipping – coastal acquisition radars, storage facilities that could be used for drones and mines, but most importantly, for missiles.”
Although the islands have been heavily bombed, many of the facilities are deeply buried, and only an amphibious raid could confirm how effective airstrikes have been and destroy any threats that survived.
‘Porcupine’ island strategy
A typical raid by an MEU would last anything from a few hours to a few days before a planned withdrawal. But to open the Strait, the marines may have to stay.
“We know how to open the Strait. It’s just very expensive and difficult,” says Peter Mansoor, a professor of military history at Ohio State University who previously served in Iraq.
“You’re going to have to seize a base in the region and establish air defence assets there to be able to shoot down missiles and drones. The Strait’s a very small place, and you have to be there to defend it. You can’t do it from afar.”
Once established, that base would create an umbrella beneath which US destroyers and minesweepers could escort convoys of cargo ships through the Strait.
But which island might US commanders choose to transform into a “porcupine” of air defences?
The largest of the islands is Qeshm, a 135-kilometre-long, 40-kilometre-wide tourist destination famed for its mangrove forests, salt caves and Portuguese ruins.
It dominates the narrowest part of the Strait, overlooks the strategic Iranian port of Bandar Abbas and may host a warren of Islamic Revolutionary Guard Corps (IRGC) military installations, making it a key military target.
The island’s defences came under attack as soon as American-Israeli forces launched the war, with more than a dozen buildings at its IRGC navy base and a Basij militia base destroyed. Another round of heavy airstrikes was reported there on March 19.
Qeshm’s size would make it a formidable target for a single MEU acting alone, however. More digestible targets would include Hormuz Island itself, the 8-kilometre wide, circular rock that lends the Strait its name, and which lies 16 kilometres from Qeshm’s north-eastern tip.
To the south of Hormuz lies Larak, another vaguely circular rock that marks the narrowest part of the Strait. It was bombed by Iraq during the 1980-88 war, and is currently used by the IRGC Navy and port authority to assess visual confirmation of the handful of vessels allowed by Iran to transit, according to Lloyd’s List. The island of Sirri, west of the Strait, hosts a deep-water oil terminal.
Of the other islands, three – Abu Musa and the Greater and Lesser Tunbs – present an intriguing diplomatic and political prize.
Seized by the Shah of Iran in 1971, they are viewed by much of the rest of the world as occupied territory legally belonging to the United Arab Emirates (UAE).
A landing confined to those islands would allow Trump to claim he has not sent troops into sovereign Iranian territory. It might also give him something with which to compensate the UAE for the disruption caused by his war. All three also have airstrips, which would help with resupply.
Iran’s hardline parliament Speaker, Mohammad-Bagher Ghalibaf, may have been referring to that possibility when he claimed on Wednesday that “Iran’s enemies, with the support of one of the regional countries, are preparing to occupy one of the Iranian islands”.
Iran would strike the “vital infrastructure” of that unnamed regional country if that happened, he added.
Another potential target is Kharg Island, a coral outcrop about 26 kilometres off the Iranian coast in the northern reaches of the Gulf.
Although often mentioned in the same breath as the other islands, Kharg is 645 kilometres from the Strait and would require a separate operation to occupy, which may explain the need for two MEUs.
It would also have a different objective. Rather than clearing out threats or using the island as a defensive base, the marines would be taking an economic hostage.
Since the late 1950s, when oil tankers grew too big for the shallow waters of the southern Iranian coast, the oil terminal on Kharg has handled the vast majority of Iran’s seaborne oil exports. Seize it, and Tehran may find it simply has to back down over the blockade of Hormuz to keep the country afloat.
At just 18 square kilometres, it is small and relatively easy to occupy. The US has already bombed military targets on the island, presumably weakening its defences.
A landing may still be costly. Iranian forces have mined its beaches, laid booby-traps and deployed extra troops with anti-aircraft weapons to the island in anticipation of an assault, CNN has reported, citing US intelligence sources.
The approach would also be risky. An MEU assigned to Kharg would be especially vulnerable sailing all the way up the Gulf within range of Iranian missile and drone fire.
And any island landing, says Burns, would eventually come up against the greatest challenge of amphibious warfare – sustaining the troops you have put ashore.
The longer they stay ashore, the more vulnerable the relatively small and lightly armed landing battalion would be to Iranian counterattack.
“Whether you seize the islands in the Strait, or whether you seize Kharg, you are still well within range of attacks from the Iranian mainland by missiles and by drones,” Milburn points out.
“Even if you seize all those islands, you haven’t opened the Strait for shipping because Iran can still threaten the Strait very obviously from the coastline.”
Seizing coastal points
If seizing an island, or islands, fails to secure the Strait, the solution to the Hormuz conundrum could become dangerously ambitious. A seaborne invasion of the Iranian mainland is, at this moment, politically and militarily unthinkable.
Yet going ashore to take out drone launch sites would be the logical next step if the “porcupine” island strategy did not work, Mansoor says.
“I don’t think the Trump administration wants to go into Iran on the mainland. But if you want to open the Strait and keep it open, you may have to seize points along the coast to be able to do that. And that sends this war into a different phase,” he adds.
This possibility makes amphibious warfare specialists shudder.
The U-shaped northern shore of the Strait of Hormuz stretches over 480 kilometres between the island of Kish in the west and the city of Bandar-e-Jask in the east.
Much of it is rugged, rocky and overlooked by a mountainous interior. Elsewhere, there are densely populated urban centres, including Bandar Abbas, a port city of half a million people.
Two MEUs may be able to mount small raids here and there, but they simply do not have enough manpower to secure the whole coast.
Even in an imaginary universe where America could deploy the marines “shoulder to shoulder” along every mile of that shore, they could not put an end to a threat to shipping generated by drones and missiles launched from inside Iran’s vast landmass, Milburn argues.
Amphibious assaults are among the riskiest operations a military can attempt, he adds.
The US has not mounted a major opposed amphibious landing since the Battle of Inchon in the Korean War – a high-risk gamble that matched the strategic stakes at the time.
The same balance of risk versus reward was present in the Falklands campaign, with British commanders opting to land on the far side of the islands to avoid fighting their way up the beaches.
That plan paid off. But the campaign demonstrated not the feasibility of amphibious operations, but rather their inherent challenges and risks.
Since then, says Burns, drones and other technology mean “amphibious warfare has changed beyond recognition”.
“I suspect you will see a lot of retired admirals saying, ‘We used to be able to do this, why can’t we do it now?’” he predicts.
“But it is not going to be anything like D-Day, or the Falklands, or even the Al-Faw peninsula during the 2003 invasion of Iraq. And it’s going to require a huge effort.”
