The announcement

Home Secretary Shabana Mahmood has announced that Iran's Islamic Revolutionary Guard Corps (IRGC) will be designated a national security threat. Under the new National Security (State Threats) Act, this designation makes it a criminal offence to express support for the organisation — punishable by up to 14 years in prison.

Draft regulations will now go to Parliament for approval. The IRGC — the military and security force answerable directly to Iran's Supreme Leader — is being designated alongside two other organisations: the Islamic Movement of Companions of the Right (IMCR) and Russia's GRU volunteer corps, a foreign military intelligence unit. Home Office minister Angela Eagle told Parliament that the Home Secretary is satisfied the legal test is met for all three.

This is not full "proscription" under the Terrorism Act 2000 — the method used against groups like Hamas — but it achieves much the same practical effect for the IRGC. Membership, expressions of support, and providing material assistance all become offences in themselves.

Why the IRGC matters

Eagle explained the government's reasoning. The IRGC, she said, is not simply a military force. It runs intelligence operations, directs proxy networks, and extends Iranian state influence worldwide — all while reporting directly to Tehran's Supreme Leader.

The political backdrop

The move follows sustained pressure from Parliament itself. The London Assembly called for IRGC proscription in March, citing at least 20 credible threats linked to the organisation inside the UK. An Early Day Motion in the Commons — a parliamentary expression of concern — made a similar demand in early March, condemning the IRGC as a state-backed terrorist organisation. Neither is binding, but both signalled broad cross-party appetite for action.

Britain had lagged behind comparable countries on this question. The EU designated the IRGC a terrorist organisation, and Argentina did so in March, aligning with the United States. As recently as 2023, the Independent Reviewer of Terrorism Legislation — a watchdog appointed to oversee counter-terrorism law — noted that the UK had not proscribed the IRGC at all, despite years of pledges from successive home secretaries.

The legal reasoning

That earlier reluctance had a legal logic. Full proscription under the Terrorism Act would have treated the IRGC as equivalent to a domestic terrorist group, with awkward effects on Britain's formal diplomatic relationship with Iran and on ordinary commercial dealings touching the IRGC's sprawling economic interests — the organisation has significant stakes in Iranian business and state apparatus alike.

The State Threats Act route, created for precisely this purpose, allows ministers to target the security threat without blurring the distinction between a hostile state actor and a non-state terrorist organisation. It is a more surgical tool.

What happens next

Parliament must approve the draft regulations before they take legal effect. Given the cross-party pressure beforehand, Commons opposition looks unlikely, though committee scrutiny of the regulations will matter — particularly around how "support" is defined for an organisation as deeply embedded in Iranian statecraft as the IRGC.

The inclusion of Russia's GRU volunteer corps suggests the government intends to use the new Act as a standing mechanism against hostile state-linked networks generally, not as a one-off response to Iran. The broader context here is that Britain is deploying new legal tools to address threats from state actors in ways that older counter-terrorism law could not easily accommodate — a shift worth noting for how security policy may evolve.

For businesses, universities, and diaspora organisations with dealings that might touch IRGC-linked entities, the practical question is where the line falls between criminalised "support" and legitimate activity. Home Office guidance will likely be as important as the regulations themselves once Parliament approves them.