Iran's Khorramshahr missile, based on a North Korean design, is reportedly capable of reaching Europe. Photo / Getty Images
The missile central to claims that Iran can now strike London is longer than a double-decker bus and based on a design from North Korea.
The Khorramshahr is around 13m long and can carry a payload of up to 4000lb (18,000kg), about the weight of a large family car.
Yet the crucial statistic of whether its range extends to the UK remains uncertain, missile experts say.
On Saturday, Israeli defence officials said Iran’s attempted ballistic missile attack on the Diego Garcia military base in the Chagos Islands – 3800km away in the Indian Ocean – meant continental Europe, and possibly Britain, were now in range.
The distance is similar to that from northwest Iran to London. Two missiles were fired, with one shot down and one failing mid-flight. It is not known how close they got to the island air base.
“London, Paris, Berlin and every other European capital now lies within credible Iranian reach,” said Brigadier General Ran Kochav, a former Royal United Services Institute research fellow and ex-commander of the Israeli air and missile force.
However, the UK government immediately expressed scepticism. Asked about the Israeli comments, Steve Reed, Britain’s Housing Secretary, said: “There is no assessment to substantiate what’s being said.
“I’m not aware of any assessment at all that they are even trying to target Europe, let alone that they could if they tried.”
Israel did not name the projectile used on the attempted strike on Diego Garcia, but it was believed to be Iran’s Khorramshahr medium-range ballistic missile.
The missile is thought to be derived from North Korea’s Musudan (BM-25) missile, which is in turn based on the old Soviet R-27, given the Nato codename SS-N-6 “Serb”.
Iran probably bought 18 of the North Korean missiles as far back as 2005, according to the Centre for Strategic and International Studies (CSIS) Missile Defence Project.
Iran first test-fired its missile in January 2017, and first publicly displayed it at a military parade in Tehran in September that year.
It had a reported range of 1900km. In 2019, Iran displayed a version with a smaller re-entry vehicle with an estimated range of nearly 3000km, the centre said.
Last month, Abbas Araghchi, the Iranian foreign minister, claimed Iran had deliberately limited the range of its missiles to 1900km.
All those stated ranges are significantly shorter than the estimated maximum range of the original North Korean version, which is up to 4000km, according to CSIS.
Analysts suggest the discrepancy means either Iran has made modifications that have reduced the range, or Tehran has been purposely understating it in order not to raise European concerns.
Brigadier General Amir Ali Hajizadeh, who commanded the Revolutionary Guards aerospace division until he was killed in an Israeli airstrike last year, said the Iranian version had “become smaller in size and more tactical”.
Decker Eveleth, a deterrence analyst, said that – adding to uncertainty – missiles did not have inherent ranges and their reach could be altered by tinkering with the payload.
A longer flight than expected need not mean Iran has made a breakthrough, or acquired new intercontinental ballistic missile (ICBM) technology.
“If you were to lower the weight of the Khorramshahr’s payload, you’d get a missile with a much longer range,” Eveleth wrote on social media. “That is probably what happened here – Iran launched a Khorramshahr with a small warhead.”
That would increase the range, but make the missile less destructive.
He said: “If you were to remove most of the payload from an existing Khorramshahr warhead, you could perhaps get that sort of range. If Iran jury-rigged that up recently, it wouldn’t necessarily point to offensive ICBM development.
“My two cents is that if it was simply a modified Khorramshahr, then the threat is pretty limited. With a small warhead and Iran’s demonstrated long-range missile accuracy, the probability you’re killing anything is pretty low at that range.
“This applies to the threat to European bases. A single small warhead against a European airfield or something similar is unlikely to cause serious damage.”
If Iran were able to target the UK, the Armed Forces would have limited options for defending it.
The UK’s only line of ballistic missile defence comes from the Royal Navy’s fleet of six Type 45 destroyers.
The warships are equipped with the supersonic Sea Viper surface-to-air missile, with a top speed of Mach 4.5. The Aster 30 variant has a range of about 120km, with each destroyer capable of carrying up to 48 missiles.
One of the warships, HMS Dragon, has been sent to the eastern Mediterranean to protect RAF Akrotiri, a British air base on Cyprus that was attacked by a kamikaze drone earlier this month.
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