Iran has designated Britain's Royal Navy and Royal Air Force as terrorist organisations and classified the Secret Intelligence Service, MI6, as a hostile group, according to a Foreign Ministry statement issued on Sunday, 1 November 2026. The measures took effect when the statement was published, reports citing the semi-official Tasnim news agency said. Tehran presented the move as reciprocal, pointing to British policy towards Iran over the past year and to London's decision in July 2026 to bring Iran's Islamic Revolutionary Guard Corps (IRGC) under its State Threats Act.

The ministry said the designations rested on a resolution of Iran's Supreme National Security Council. MI6 was placed under a provision of Iran's law on tougher penalties for espionage and cooperation with Israel and hostile countries, while the Royal Navy and RAF were brought under Iran's law on reciprocal action against the United States' designation of the IRGC. Tehran described British policy as hostile and unlawful, citing what it called Britain's involvement in the US-Israeli war against Iran through bases, facilities and logistical support. Those characterisations are Iran's own; no UK government response had been published at the time of writing.

Why London's July decision matters

On 13 July 2026, the UK announced that the IRGC would be among the first bodies designated under the new National Security (State Threats) Act 2026. London said supporting or assisting a designated group could carry up to 14 years in prison, and that it had already sanctioned the IRGC in full. Iran has used reciprocal terrorist designations before, notably against US Central Command after Washington designated the IRGC in 2019.

What happens next is unclear

The Iranian ministry did not spell out any operational consequences for British ships or aircraft, and the step appears mainly legal and political for now. Its practical effect will depend on how Tehran applies it, particularly for British naval and air activity in the Gulf at a time of heightened maritime tension. The absence of a published UK response leaves the diplomatic fallout, and any further retaliatory steps, still to unfold.