U.S. Ramps Up Defenses for Naval Support Facility Diego Garcia

 

A number of recent satellite passes over Diego Garcia – historically part of the British Indian Ocean Territory, now part of Mauritius - have identified the presence on the airfield of up to six F-15 strike aircraft. There are normally no US aircraft permanently stationed on Diego Garcia, with aircraft deployed only for specific short-duration tasks and missions. The presence of the F-15s on Diego Garcia has been confirmed by official Indo-Pacific Command channels, which have specified that the aircraft in question are F-15Es with a dual air-to-air and air-to-ground/sea mission capability. This acknowledgement advertises that the deployment is meant for deterrence purposes, to warn off a potential adversary and to give notice that a threat has been identified and can be dealt with. The nature of the threat remains undefined, but there are a number of possibilities to be considered.

Iran’s Islamic Revolutionary Guard Corps (IRGC) specifically has referenced and threatened the US naval and air presence on Diego Garcia on numerous occasions, alongside general threats made recently to target any foreign bases from which the United States would mount an attack on Iran. Rear Admiral Alireza Tangsiri, the IRGC Navy (Nedsa) commander, has said that converted tankers Shahid Mahdavi (110-3) and Shahid Bagheri (110-4) are configured to undertake long-range deployments and can be equipped with both ballistic missiles and drones. The Admiral noted that the Shahid Mahdavi had “cruised in the area of American forces stationed on Diego Garcia” on a 40-day deployment through the Indian Ocean cruise, which ended on May 18, 2024. Both ships have demonstrated the capability to fire Fateh-313 missiles with a range of 500 kilometers, as well as medium-range drones.

In the latest satellite imagery available, both the Nedsa drone carriers were at anchor in the Bandar Abbas roads (Shahid Mahdavi at 27.0693N 56.1881E and Shahid Bagheri at 27.0878N 56.2001E), and have been so since at least the beginning of May. However, while the threat focus is usually on these two ships, other Nedsa ships can also launch missiles and drones.

An article published by Iran’s Press TV on September 23, 2024, also noted that Diego Garcia would be within range of the IRGC’s Shahed-136B drone, if launched from Iran’s south-east coast.

At such range, neither the regular Iranian Navy nor Air Force could realistically press home an attack on Diego Garcia. In April 1981, during the Iran-Iraq war, the Iranian Air Force demonstrated that it had the ability to mount attacks in depth, destroying 25 Iraqi aircraft on the H-3 airfields close to the Jordanian border. Although the Iranians still have the very same aircraft in service, their reliability is now dubious, and the range to Diego Garcia is much greater, making such an operation unfeasible. The Iranian Navy is proud of its 86th Flotilla round-the-world cruise in 2022, but its frigates and the single operational Kilo-class submarine would be vulnerable and lack the support necessary to operate at long range.

Any IRGC attempt to attack Diego Garcia would be limited in scope, and might yet rely on a novel attack concept not yet unidentified. To get close, they would have to rely on surprise and on remaining undetected in the deep ocean. But the Iranians are unlikely to know how effective US surveillance is - and with the F-15Es now protecting the island, are unlikely to want to try and find out.