The airbase that could be used to launch bunker-busting strikes on Iran has seen an influx of heavy American bombers and fighters.
Satellite images taken three days ago show the presence of four B-52s that can technically drop the 13,600kg GBU-57 bomb needed to penetrate Iran's underground nuclear network.
They were spotted by commercial satellite imagery company Planet Labs, and traces how the balance of aircraft at the base has changed as the situation in the Middle East deteriorated.
Six F-15 multirole warplanes have also arrived in recent days and would be used to protect the airbase from Iran drone or cruise missile attack.
Six KC-135 tankers are also there, giving America the option to refuel aircraft on the approach to Iran if required.
There is also the prospect that with aircraft movement into Diego Garcia remaining fluid, B-2 Spirit stealth bombers could also land there, having been spotted in recent months.
Diego Garcia, the largest of the Chagos Islands, has been used as the site of a joint UK-US military base since the 1970s due to its strategically important position in the Indian Ocean.
The UK recently signed a deal to return the Chagos Islands to Mauritius, with an agreement to lease Diego Garcia for £101 million each year for the next 99 years. Critics of the deal said the UK risks losing an important strategic presence in the Indian Ocean.
Diego Garcia would likely be used as a base for a “stand-off” attack on Iran, The National has been told.
“While they can drop the GBU-57, the fact they have to fly straight and level means that the B-52 would be sitting ducks if used over Iran,” said military aviation expert Tim Ripley. “But they carry 20 cruise missiles, which they can launch from a distance.”
The total value of the jets currently present is approaching $1.5 billion which contrasts with the $12 billion cost of the six B-2s that were at the base two months ago and appear to have been moved back to the US.
It is understood that they were there to be used against the Houthis in Yemen as part of America’s bombing campaign before a ceasefire was agreed.
They are the most expensive aircraft ever built and the only ones certified to drop GBU-57 bombs. Their departure makes it more likely that if US President Donald Trump decides to support Israel by attacking Iran’s Fordow nuclear facility hidden in a mountain, the strike will be launched from America.
The B-2s would fly from their Whiteman air force base in Missouri direct to the site near Qom − a distance of 11,200km distance. While that is at the very limit of their range, they will be able to receive air-to-air refuelling from tankers stationed in the Middle East and Europe.
The Diego Garcia deployment is part of a widespread movement of US warplanes into the region as the possibility of a US attack on Iran increases.
A fleet of more than 30 air-to-air refuelling tankers have crossed the Atlantic and are now stationed at airbases across Europe and the Middle East.
They have been joined by squadrons of F-22 and F-35 stealth fighters that will be on hand for a major air attack alongside the jets from what will soon be two US aircraft carriers in the region, once the USS Nimitz arrives from the Pacific.
But as the Diego Garcia base is a British overseas territory, permission would be required from London before any raid on Iran is undertaken.
The UK is likely to face domestic opposition to joining the US in the conflict. Prime Minister Keir Starmer held an emergency Cobra meeting upon his return to the UK from the G7 summit to discuss the UK's response to the crisis.
Attorney General Lord Richard Hermer reportedly raised concerns about the legality of the UK’s involvement, advising that the UK should limit this to “defensive” support.
However, Sir John Sawers, former head of MI6, on Thursday told the Chatham House think tank's London Conference that he did not see obstacles to a UK green light for use of the archipelago for an Iran mission.
“If American bombers do strike they will almost certainly do so from Diego Garcia,” he said. “We’ve just negotiated a long-term lease so there could be an American base on Diego Garcia. I don't see Keir Starmer saying, ‘oh, but you can't use it. I'm afraid’. I don’t see that.
“It’s very straightforward. They’ve got an American base there and whole purpose of Diego Garcia is so the Americans can use it when they need to use it.”
There are some concerns that further escalation with Iran would have the undesired effect of re-enforcing its nuclear ambitions. Former National Security Adviser Lord Peter Ricketts said the UK “should not” support potential US strikes on Iran.
“The only way we're going to control Iran's nuclear ambitions in the long term is by having a deal with them,” he said.
“I think just coming back and bombing them every few years is not going to make the world safer. In fact, it's going to reinforce their determination to keep working on a nuclear weapon when this round of fighting is over,” he said.
