On Saturday, March 22, the Israel Defense Forces stated that Iran now has ballistic missiles capable of reaching up to 4,000 kilometers. That would put London (approximately 4,400km from Tehran), Paris, and Berlin within potential range. Israeli Prime Minister Benjamin Netanyahu separately insisted Iran has "the capacity to reach deep into Europe." UK Housing Secretary Steve Reed, speaking the same day, said there is "no specific assessment that the Iranians are targeting the UK — or even could if they wanted to." Iran's own foreign minister said earlier this month that Iran had deliberately capped its missile range at 2,000km.
And yet: Iran fired two ballistic missiles at Diego Garcia on Thursday night. Diego Garcia is approximately 3,800km from Iran.
At least one of these positions is wrong. This article lays out what is known and what is in dispute.
The Four Competing Claims
Claim 1 — IDF (Saturday, March 22): Iran has missiles capable of reaching 4,000km. The IDF said it had revealed this last year — that Tehran had "intended to develop" missiles capable of reaching Europe, Asia, and Africa. "We have been saying it: The Iranian terrorist regime poses a global threat. Now, with missiles that can reach London, Paris or Berlin."
Claim 2 — UK government (Saturday, March 22): "There is no assessment to substantiate what's being said." Housing Secretary Steve Reed, asked directly about the IDF's claim: "no specific assessment that the Iranians are targeting the UK or even could, if they wanted to." UK Prime Minister Starmer's government separately noted that the longest-range weapon in Iran's known arsenal has a maximum range of approximately 2,000km.
Claim 3 — Iran's foreign minister (earlier in March): Iran has "deliberately capped its missiles' range at 2,000km, as 'we don't want to be felt as a threat by anybody else in the world.'" This is a diplomatic statement, not a technical declaration — it is Iran's stated policy position, not a verified capability limit.
Claim 4 — The physical fact: Iran fired at Diego Garcia. Diego Garcia is approximately 3,800km from Iran, per BBC reporting. If the missiles were launched from Iranian territory and targeted Diego Garcia, they traveled — or were intended to travel — a distance nearly twice the claimed 2,000km cap and within the IDF's stated 4,000km range.
Why the Gap Between 2,000km and 3,800km Matters
Iran's confirmed ballistic missile arsenal — the weapons publicly assessed by Western intelligence and open-source analysts before this war — includes the Shahab-3, Ghadr-110, and Khorramshahr series. These systems have been assessed at ranges broadly between 1,300km and approximately 2,000km with standard warheads.
The key technical caveat, raised by Dr. Sidharth Kaushal of the Royal United Services Institute (RUSI), is that "missile range is an elastic thing — if you put a lighter warhead on a missile, you can extend its range." A missile designed to carry a 750kg warhead to 1,500km might carry a 250kg warhead to 3,000km or more. The trade-off is payload — the weapon delivers less explosive force at longer distances.
This matters for the Diego Garcia question. If Iran launched at Diego Garcia — which is beyond any publicly confirmed Iranian missile range — one of three things is true:
Option A: Iran used a publicly known missile at reduced payload, extending its range to 3,800km. This would confirm the IDF's general claim that range can be extended, though perhaps not to 4,000km with meaningful warheads.
Option B: Iran used a previously undisclosed long-range system — one not in the public assessments. This would represent a significant intelligence failure and would validate Israel's broader claim about undisclosed capabilities.
Option C: The missiles did not originate from Iranian territory. They could have been fired from a closer launch point — a ship, a proxy force, or a staging location in the Indian Ocean region. The US military has declined to comment on the incident, which makes this option impossible to rule out.
The US military's silence is notable. A confirmed Iranian ballistic missile strike from Iranian territory at 3,800km would be a major intelligence and military development. The absence of official US confirmation — only WSJ and CNN reporting citing unnamed officials — leaves all three options open.
What the Experts Say
Dr. Kaushal's RUSI analysis frames the question carefully. He said it was "probably accurate" that Iran had missiles capable of reaching the UK — but added that this was "not the most pressing threat" because such weapons would be inaccurate at extreme ranges and would have to penetrate well-defended airspace. His key question: "So what? If you can launch a small number of conventionally-armed ballistic missiles over well-defended airspace... and they're quite inaccurate at very long ranges… what would the Iranians be trying to achieve?"
This reframes the debate from capability (can they hit London?) to utility (what would it accomplish?). A long-range missile with a reduced warhead, traveling through NATO-defended European airspace, has high probability of interception and limited blast effect if it gets through. It is a signaling weapon, not a precision strike weapon — more useful for threatening than for destroying.
Retired British Army General Sir Richard Shirreff — former NATO Deputy Supreme Allied Commander Europe — offered a different angle. He said the IDF's claims should be taken "seriously, but as seriously as the potential for Russian missiles to come this way as well." He added: "Israel is going to say this, because it is in Israel's interest to broaden the war, to bring as many nations in on this war." This does not mean the capability claim is false — but it identifies an incentive to overstate it.
The Intel Gap and Why It Can't Be Closed Publicly
The core problem is that the definitive answer to this question — does Iran have operational ballistic missiles capable of reaching 3,800km+ with meaningful payloads? — almost certainly exists in classified intelligence assessments held by the US, UK, and Israel. None of those governments will publish it.
What they will do is selectively release characterizations of that intelligence for policy purposes. The IDF has an incentive to present the threat as large and broadening — it strengthens the case for continued international support and justifies escalatory action. The UK government has an incentive to present the threat as limited — it helps maintain its position that it is not a direct target and therefore need not take offensive action. Iran has an incentive to claim self-restraint — it signals that it is not threatening non-combatants, which limits international justification for additional intervention against it.
None of these characterizations are necessarily false. They can all be partially true and still be used selectively.
What the Contradiction Means Practically
For the UK, the immediate policy question is whether to treat Iran as a direct threat to British territory. Reed's answer on Sunday was unequivocal: no assessment supports treating it that way. UK military involvement remains officially limited to allowing US use of British bases, not direct participation in strikes.
For NATO allies watching from Europe, the IDF's claim — even if disputed — shifts the psychological framing of the conflict. A war between the US, Israel, and Iran that was previously understood as a Middle East regional conflict becomes something different if Iran has demonstrated or asserted the capability to reach European capitals.
For the factual record: Iran fired at a base 3,800km away. The missile or missiles used to do that are not publicly identified. The US military has not explained what system was used. Until it does — or until an independent technical assessment is released — the question of whether Iran can hit London remains genuinely unresolved in the public domain.
The US military has not commented. That silence is itself information.