THE ECONOMIST: How would American ground forces take Kharg?

Kharg island is one of those patches of land that has had the misfortune to be a recurring backdrop to military history.

Jimmy Carter and Ronald Reagan both considered invading it. Saddam Hussein bombed it. So has Donald Trump, who in 1988 said that were he president, he would “do a number” on the island.

Although Mr Trump now says that the Iran war might end in a few weeks, and that he will give a televised address on the evening of April 1 with an “important” update on its progress, he has a history of feints and misdirections. And he has also said that he might “take” the island.

It is an export terminal for 90 per cent of Iran’s oil, which is pumped in by pipeline.

“If you grab Kharg, you basically have their oil export capability hostage,” says Seth Krummrich, a former chief of staff of US Special Operations Central, which deals with the Middle East.

Mr Trump could use the island as a bargaining chip, potentially returning it in exchange for Iran reopening the Strait of Hormuz.

America has already softened up the island’s defences, striking 90 military targets but sparing its oil facilities.

Taking Kharg “is certainly within the capabilities” of the American armed forces, says Joseph Votel, a former commander of centcom, which runs Pentagon operations in the Middle East (now at the Middle East Institute, a think-tank). But seizing and holding the island would present its own risks.

The first challenge is getting boots on the island. In recent weeks, America has deployed various units that could be used in ground operations.

The 31st Marine Expeditionary Unit — a group of around 2500 marines, with the USS Tripoli, an amphibious assault ship, at its core — is in the Middle East, having been sent from Japan.

The 11th MEU will arrive in a couple of weeks from California. The Pentagon has ordered 2000 elite paratroopers from the army’s 82nd Airborne Division to the region, possibly an advance for many more. Several hundred special-operations forces have also arrived in the Gulf.

Former military officials estimate that America would need at least a battalion of combat forces, roughly 1000 troops, to take Kharg.

With the Strait of Hormuz under fire, marines would struggle to get their ships and landing craft into place for an amphibious assault.

An airborne assault, with planes ferrying soldiers and equipment to the island, would also be risky.

Kharg has an airstrip, but Iran could bomb that. And since the airstrip is the obvious drop zone for paratroopers, Iranian forces would surely be waiting for them there.

Instead, soldiers would probably attack Kharg by helicopter. The 31st MEU practised a similar assault in the Pacific last year.

Nearly 400 marines were flown in helicopters for 1600km from ship to shore — more than the distance they would cover from Oman to Kharg.

The Pentagon would probably establish a nearby staging area where helicopters could be refuelled, boosting their rate of sorties.

The assault helicopters would need surveillance aircraft, warplanes and attack helicopters as escorts. Upon approach, they could face fire from small arms as well as from portable air defences.

Getting those troops to Kharg is only the first step. They would then need to clear and hold it, under fire from Iran.

The Islamic Revolutionary Guard Corps, Iran’s elite paramilitary force, has reportedly scattered anti-personnel mines on the island and still has troops there.

The marines could try to use helicopters to deploy short-range air-defence systems to the island. But, given their weight and the distances involved, landing ships might be required to move them. That leaves soldiers vulnerable.

One option is to rely on attack helicopters and fighter jets circling protectively overhead, striking Iranian missiles or drone teams.

That could tie up large numbers of aircraft for an indefinite period. America also has air defences on ships but many are running low on interceptors.

“The Iranians can saturate that island with whatever it is they have left,” says Kevin Donegan, a retired admiral who commanded the us Navy’s Fifth Fleet, which operates in the region.

American forces could blunt Iran’s aerial threat using Kharg’s oil infrastructure as cover.

Ground forces could dig in around the pipelines, storage tanks and shipping terminals, goading Iran into hitting its own oil facilities.

That would put the Iranian regime in the awkward position of having to decide whether it is “willing to destroy (its) own oil economy to kill some Americans”, suggests Mr Krummrich.

The problem is not just getting to the island and parrying projectiles.

An expeditionary unit carries only two weeks of supplies; an airborne brigade much less.

Initially, much of the resupply effort would probably rely on helicopters or other aircraft that can carry little.

Planes could drop more supplies. But each time American forces sent in new equipment or other goods, they would need to re-establish complex aerial convoys similar to those that brought troops to land, says Mr Votel. That would not be easy, or cheap.

The broader question is whether holding Kharg would serve Mr Trump’s aim: to “take the oil”.

Iran could shut off the pipelines to the island, perhaps diverting some to oil terminals down the coast, which can handle a quarter of Kharg’s volumes.

If the oil continues to flow, Mr Trump would need to get it out via Hormuz. It would be far simpler to grab Iran’s oil exports — still more than 1.5 million barrels a day, remarkably — from tankers at sea, much as Mr Trump did with Venezuela.

That, though, would not have the drama of America’s largest airborne assault in nearly 40 years.