In a tree-lined business park in Chiswick, West London, there is a heavy presence of armed police. Black, multi-role armoured vehicles called Jankels are positioned at intervals alongside Met Police armed response vehicles, fully crewed-up with armed officers inside.

They are guarding every approach to the plate-glass building that houses the offices of Iran International, an independent Farsi-language news channel that has incurred the fury of Iran's regime.

"This has to be the biggest armed police operation around a commercial building in this country that I can think of," says a spokesman for Iran International.

It is certainly reminiscent of Tony Blair's deployment of armoured vehicles to Heathrow in February 2003 in response to a perceived terror threat.

Founded in 2017 by a former BBC Persian journalist, Iran International broadcasts into Iran by satellite. It has been providing 24-hour rolling news coverage of the huge street protests that have engulfed Iran since the death in police custody of 22-year old Mahsa Amini, allegedly arrested for not wearing her hijab head covering correctly.

Many of the protests have been calling for an end to the oppressive rule of the Islamic Republic.

But instead of listening to people's demands, the authorities in Iran have arrested thousands and accused Western nations and the free media they host of stirring up the protests and provoking unrest.

So far, so familiar. That has been the refrain each time protests in Iran have erupted, but this time it's different.

Not only are the protests significantly more widespread, but the Iranian Revolutionary Guards Corps, the real power behind the regime, has been targeting Iranian opposition journalists based in Britain.

"Iran projects threat to the UK directly, through its aggressive intelligence services," says Ken McCallum, the director-general of MI5, the UK security service.

"At its sharpest, this includes ambitions to kidnap or even kill British or UK-based individuals perceived as enemies of the regime. We have seen at least 10 such potential threats since January alone."

The Foreign Secretary James Cleverly has called on Iran to stop its intimidation of UK-based journalists. Iran has called the accusations "ridiculous".

Working closely with MI5, the Metropolitan Police has responded to the threats with a large show of force to protect the 100 or so employees of Iran International in Chiswick, some of whom have personally received death threats.

"The Met Police have been outstanding", the Iran International spokesman tells me as we sit in an office next to their newsroom. "Their response has been swift and effective."

So what form do these threats take exactly?

Initially they were just text messages, sent to the mobile phones of journalists, often warning them that if they don't stop their critical coverage of the regime then their families and relatives in Iran will suffer.

That apparently has been going on for years, targeting not just Iran International but BBC Persian as well, to the point where Iran's behaviour has been raised at the UN.

But this year Iran has gone further.

It seems that planning discussions of actual attacks have been intercepted by UK intelligence. There has also been hostile surveillance spotted outside both the offices of Iran International and the homes of some of its staff.

"We're talking here about low-grade Tier 3 operatives being hired and directed by Tier 1 operatives," says the Iran International spokesman.

"They are easily recruited from drug gangs or from the fringes of an Islamic centre."

The hostile surveillance has not always been that sophisticated, he says. One example he gives is of two men and a woman wheeling a pram up and down outside the building on a cold evening while taking photographs - at 11pm.

"Who takes a baby in a pram for a walk at that time of night?"

There have also been attempts to interfere, unsuccessfully, with Iran International's satellite broadcasts, as well as the usual cyber activity.

He shows me a text from an employee who has just been alerted to attempts to hack into his Twitter account. Then, abruptly, our meeting ends.

"I've got two protective security officers coming in from the Met to discuss what more still needs to be done. This problem is not going away," he tells me. (BBC)

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