On Friday, the UK Home Office formally designated Iran's Islamic Revolutionary Guard Corps (IRGC) under the new National Security (State Threats) Act 2026, making it a criminal offence to support, assist, or receive material benefits from the organisation, punishable by up to 14 years in prison. Acts of sabotage carried out on its behalf could lead to life imprisonment. The designation, approved by Parliament the previous day, also applies to the Islamic Movement of the Companions of the Right (IMCR) and Russia's GRU Volunteer Corps.

From London, the outgoing government of Prime Minister Keir Starmer framed the measure as necessary to counter state-sponsored threats, including espionage, sabotage, and intimidation through proxies. The Home Office stated that the new legal tool grants security services broader powers to pursue hostile activity without needing to prove a direct link to a foreign state in every case. In Tehran, the Iranian Foreign Ministry issued a statement condemning the designation as "unjustified, irresponsible, and contrary to fundamental principles of international law," including sovereign equality and non-interference. It summoned the British ambassador, Hugo Shorter, to convey a formal protest and warned that any hostile legislation would be met with a "firm and reciprocal response." Iranian officials stressed that the IRGC is an integral part of the country's official armed forces, responsible alongside the army for defending territorial integrity and national security.

The new designation differs from a proscription under the Terrorism Act 2000, which the UK has not applied to the IRGC. Instead, it creates a parallel mechanism that criminalises support without formally labelling the group a terrorist organisation. Legal analysts in London note that this approach avoids the diplomatic and legal complexities of a full proscription while still enabling prosecutions. The law also places the IRGC in the highest tier of the Foreign Influence Registration Scheme (FIRS), imposing strict legal constraints on any activity or association with the group inside the UK. The move follows a series of security incidents, including the 2024 stabbing of a British-Iranian journalist, which British prosecutors linked to IRGC-directed surveillance and planning.

The UK's action is part of a broader Western effort to constrain Iranian influence operations abroad. Viewed from Washington, the designation aligns with long-standing U.S. policy, which has listed the IRGC as a foreign terrorist organisation since 2019. European capitals have been more cautious, balancing security concerns with diplomatic channels. The inclusion of the Russian GRU Volunteer Corps in the same designation underscores London's assessment of a coordinated threat from state actors using proxy networks. Iran, for its part, has consistently rejected such designations as politically motivated and a violation of its sovereignty, and has previously responded to similar measures with tit-for-tat listings of Western military institutions.

With the law now in force, the immediate next steps centre on enforcement and potential diplomatic fallout. The UK Home Office has indicated that police and security services will begin applying the new powers to monitor and disrupt IRGC-linked activity. Iran has reserved the right to take reciprocal measures, and its Foreign Ministry has placed responsibility for any political, legal, and diplomatic consequences on the British government. No further parliamentary action is required, but the dossier remains open as both sides assess the practical impact of the new legal regime.