On Sunday morning, an apparent terrorist attack against the Royal Air Force Fairford base was narrowly averted after the arrest of five men in three vans in the village of Whelford. While the police investigation is in its early stages, the activities of the security services at the scene suggest that the alleged terrorists planned to use the vans as car bombs.

In off-the-cuff remarks, US President Donald Trump said that “we had them under view for a long time” and America “worked with a lot of [British agencies]” to stop the attack. According to Whitehall sources, however, the Government’s response was not an “intelligence-led operation”.

This is alarming because the visible scale of what was planned would make this one of the most serious terrorist plots in some time. While it is not as potentially lethal as Al-Qaeda’s 2006 airlines plot, it is still a significant escalation from the low-tech operations in the Islamic State’s terrorism wave in the 2010s. There is still much that is unknown about the RAF Fairford incident; a possible explanation for the difference is that this attack was state-sponsored.

The primary suspect, on which security services are known to be focusing, is Iran. The Iranians publicly “warned” Britain in March that allowing the Americans to use its bases in the ongoing war was viewed as “participation in aggression”, and RAF Fairford has hosted American warplanes involved in the war, including over this weekend. The Iranian threat to Britain is not determined by specific “grievances”, though.

Iran orchestrated a series of terror attacks in Britain earlier this year, and Britain has been a target of the Islamic regime since shortly after the Islamic Revolution in 1979. If Iran does prove to be behind the RAF Fairford incident, it would only underline the permanent threat Iran poses to Britain — and the reckless course that Labour has taken with national security.

Iran’s Islamic Revolutionary Guards Corps (IRGC) has struggled to carry out “successful” attacks in the West for many years because Israel has thoroughly infiltrated the IRGC’s foreign attacks apparatus. Tel Aviv routinely provides the intelligence for Western governments, Britain included, to prevent Iranian terrorist activity on their territory, saving untold numbers of lives.

Britain’s reliance on Israeli intelligence was the reason the Secret Intelligence Service (SIS or MI6) warned Foreign Secretary Ed Miliband against imposing sanctions on Israel earlier this month. And the risk that intelligence sharing with the Israelis is disrupted extends to Britain’s influence in foreign affairs.

Miliband compounded this last week by meeting with Iran’s Foreign Minister, Abbas Araghchi, the man who threatened Britain back in March. Meeting hostile actors is part of the Foreign Secretary’s job description, but that is not how Miliband treated the occasion. He made no mention of Iranian terrorism in Britain, and the meeting was, instead, a gift to the Islamic regime’s propagandists.

So could this be the start of a wider campaign against Britain? Iran regularly runs terrorist operations out of its embassies, and if it is shown to be behind the RAF Fairford plot, that is likely how it will have been organized. The retaliatory measures would therefore likely include the expulsion of Iranian diplomats known or suspected to be undercover IRGC officers. There is a case for doing this anyway as part of a package of measures to disrupt Iran’s current escalatory course in Britain. Resetting the tone of diplomatic engagement to recognize Iran’s hostility would be a start. Another step is resolving the current slightly strange status of the IRGC by adding it to the proscribed terrorist list, which would also make it legally easier to dismantle the Iranian propaganda recruitment system in Britain.

Regardless of the outcome of the investigation into RAF Fairford, the Islamic regime has become dangerously emboldened by Britain’s current approach to Tehran. Measures to dissuade Iran from further escalation are urgently needed. If not, this thwarted attack could just be the first in a steep escalation of tensions.