US President Donald Trump has indicated that he may send troops to seize control of Iran's key oil export terminal at Kharg Island in the northern Gulf. So what's behind this, how would it work and what are the risks?
Kharg Island has long been Iran's chief outlet for its oil exports. The island sits offshore with waters deep enough to load product onto tankers known as Very Large Crude Carriers (VLCCs), which can hold around two million barrels. Around 90% of Iran's oil exports pass through Kharg.
During the Iran-Iraq war in the 1980s it was frequently bombed by the Iraqi Air Force, and on 13 March this year the US struck what it said were 90 military targets on the island. However, it spared the oil infrastructure.
If the US does decide to invade Kharg Island, it would most likely be a temporary measure intended to put pressure on Iran by cutting off its fuel exports until it relinquished its choke-hold on the Strait of Hormuz - one of the world's busiest oil shipping lanes - and conceded to Washington's demands.
Given the resilience and defiance of the Iranian regime, it is highly questionable whether this would work. The speaker of Iran's parliament, Mohammad Bagher Ghalibaf, has warned that his country's forces would rain down fire on any invading US forces. Iran is believed to have reinforced its defences on the island, including with surface-to-air missile batteries.
Iran has also accused the US of duplicity by proposing peace talks at the same time as dispatching troops to the region. These forces consist of nearly 5,000 US Marines and around 2,000 paratroopers from the 82nd Airborne Division, which has prompted widespread speculation that either or both could be used to seize and hold Kharg.
In theory, the paratroopers could make an airborne assault, probably at night, to seize key positions on this small island, which measures just 20 sq km (7.7 sq miles). The US Marines would deploy from ships equipped with Osprey tilt-rotor aircraft and Landing Craft Air Cushioned (LCAC) for making amphibious landings; but first, those ships would have to run the gauntlet of getting through the Iranian-controlled Strait of Hormuz.
Any landing, by air or sea, would expect to be met with anti-personnel mines and swarms of drones. Such is the awesome fighting power of these Marine Expeditionary Units (MEUs) that the US force would almost certainly prevail, but it could come at the expense of severe casualties.
The US would then face the problem of holding the ground for an indeterminate period while subject to bombardment from the Iranian mainland. A comparable scenario is Ukraine's Snake Island in the Black Sea, which Russia seized early on after its full-scale invasion but was subsequently driven off by constant harassing fire from the Ukrainian mainland.
A lengthy US occupation of Iranian territory would be unpopular back home in the US, including with some of Trump’s supporters who elected him partly on a promise to avoid these sorts of conflicts. There has been so much talk of a potential US ground assault on Kharg that it could be part of a deception plan.
With Kharg's strategic value to Iran and the Islamic Revolutionary Guards Corps, there are also other islands in the Gulf that could be targets, such as Larak Island and Qeshm, which have significant military implications.
As tensions continue to escalate, President Trump has remained ambiguous about the next steps, stating that the US is in serious discussions with Iran. However, bridging the gap between US and Iranian positions remains a formidable challenge.
