Why Iran targeted Diego Garcia and what it reveals about its missile range

This satellite image released by Planet Labs PBC shows six American B-2 bomber planes on the tarmac of Mauritius' US military base on Diego Garcia island.

• Iran fired two missiles at US-UK base Diego Garcia, both missed
• Attempt shows Iran's missile range may exceed previous estimates
• Khorramshahr-4 missile possibly used, range up to 2,000 km

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Iran fired two intermediate-range ballistic missiles toward the joint US-UK military base at Diego Garcia in the Indian Ocean, but neither hit the target, according to a report by The Wall Street Journal citing US officials.

One of the missiles failed in flight, while a US warship launched an interceptor at the other, although it remains unclear whether the interception was successful. The report did not specify when the missiles were fired.

Britain has condemned “Iran's reckless attacks” after its military fired missiles at the UK-US air base on the island of Diego Garcia in the Indian Ocean.

UK officials have not given details of the attempted strike, which was unsuccessful. It's unclear how close the missiles came to the base, which is about 2,500 miles (4,000 kilometres) from Iran. The Ministry of Defence said on Saturday that Iran's “lashing out across the region and holding hostage the Strait of Hormuz, are a threat to British interests and British allies.” Britain has not participated in US-Israeli attacks on Iran, but has allowed American bombers to use UK bases to attack Iran's missile sites.

Conflicting reports and strategic signal

Iran’s semi-official Mehr News Agency reported on Saturday that Tehran had fired two ballistic missiles at the base, describing the move as a show of capability.

Mehr said targeting the base was a "significant step ... that shows that the range of Iran's missiles is beyond what the enemy previously imagined".

The base, located around 2,500 miles (4,000 kilometres) from Iran, is a key strategic hub used by US forces for operations across Asia, including past campaigns in Afghanistan and Iraq.

Missile capability in focus

The attempt to strike Diego Garcia suggests that Iran’s missile range may be greater than previously acknowledged, with reports indicating the possible use of the Khorramshahr-4 missile.

“Nobody, and I mean nobody, even guessed” Iran had missiles with that range, said William Alberque to Bloomberg, a Europe-based senior fellow at the Pacific Forum. “It means they probably used a modified missile, maybe a prototype,” indicating Tehran still had storage or workshops that could make the alterations.

Iran could have removed weight from an existing missile or even taken off the warhead to extend its range, Alberque said. It could also have been a one-off modified design, he added.

The Kheibar missile, the latest version of the Khorramshahr which is Iran's longest-range missile to date, was unveiled alongside a replica of the Al-Aqsa mosque in east Jerusalem, in a live broadcast on state television.

State news agency IRNA said the Kheibar is "a liquid fuel missile with a range of 2,000 kilometres and a 1,500 kilogrammes warhead".

Its name references the ancient town of Khaybar -- located in modern-day Saudi Arabia -- known for a decisive seventh-century battle in which the army of Prophet Mohammed defeated its thousands of Jewish residents.

According to state media, the speed of the high-mobility tactical missile "can reach Mach 16 outside the atmosphere and Mach 8 inside the atmosphere".

The reported targeting of the US-UK military base at Diego Garcia has drawn attention to the sheer distance involved, with the base located roughly 3,800 to 4,000 kilometres from Iran — far beyond the publicly stated range of its missile arsenal.

Iranian media on WSJ report of 4,000 KM+ ATTACK on Diego Garcia Base:

'Iran has effectively COUNTERED all American threats against it with retaliatory attacks' https://t.co/wukEcd3FDSpic.twitter.com/WsH3FjghmI — RT (@RT_com) March 21, 2026

Iranian officials have previously maintained that their missiles are limited to around 2,000 kilometres, making the reported strike attempt significant in terms of capability.

“4,118 km from Iran to Diego Garcia. Far beyond any previously known Iranian ballistic missile range,” a netizen said in a posy on X.

Missile range debate gains momentum

Steve Lookner of Agenda-Free TV also noted, “Iran’s targeting of Diego Garcia, about 4,000 kilometers from Iran, implies its missiles have a greater range than Tehran has previously acknowledged.”

Diego Garcia lies 3,795 kilometers (about 2,358 miles) from Iran, raising new questions about the true range of Tehran’s missile capabilities.

Iranian Foreign Minister Abbas Araghchi had previously stated that Iran had intentionally capped its missile range at 2,000 km.

Conflicting estimates on missile capabilities

However, Wisconsin Project on Nuclear Arms Control, through Iran Watch, said that Iran possesses operational missiles capable of reaching 4,000 km. Meanwhile, Alma Research and Education Center estimated a range of around 3,000 km, with reports indicating ongoing development of longer-range systems.

As per the education centre, citing the Israel Defense Forces, by February 2026, this had grown to about 2,500 missiles after the conflict with Israel, which saw many of their missiles destroyed. According to their report, Tehran’s mid-range missiles can travel between 1,000 and 3,000 km.

As per reports, the Khorramshahr missile has the longest range between 2,000 – 3,000 km. Next is Emad with a 1,800 km range and Ghadr which can have a 1,600–2,000 km range.

Shahab-3 has a 1,300 km range and Rezvan has a 1,400 km range.

Why Diego Garcia matters

The targeted base on Diego Garcia holds major strategic importance. Located on a remote island in the British Indian Ocean Territory, it serves as a key hub for US and UK military operations, hosting bombers, nuclear submarines, and guided-missile destroyers.

The base is operated primarily by the US and serves as a critical hub for air and naval operations across a vast region spanning Africa, the Middle East, and Asia. The base has played a central role in US military campaigns in Iraq and Afghanistan, providing a launch point for long-range bombers and supporting naval deployments, including submarines and surveillance missions.

Its remote location makes it a secure site for pre-positioning military supplies, fuel and equipment, enabling rapid response during regional crises.

Diego Garcia is also seen as vital to Washington’s strategic posture in the Indian Ocean, allowing it to monitor and counter activities by rivals such as Iran and China. Its isolation and heavy fortification make it one of the most secure overseas military installations available to the US.