You're sitting at your desk, and you click on something in your email, or on a website, that you shouldn't.

Some blinking red box flares onto your screen, and you know you're in trouble. Worse yet, maybe everything goes black and your computer has just become the world's most expensive fishing weight.

Now just imagine instead of your computer, it's your city.

It's not impossible, according to a new report from Telegraph, which cites the alarming statements from Robert Hannigan, the U.K.'s Government Communication Headquarters chief.

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During a rare recent public appearance, at the Cheltenham Science Festival, he said there are nation states developing programs that could attack and shut down significant assets. For example, a major city.

Terrorist groups also are trying to acquire the expertise needed, he said.

"At some stage they will get the capability," he said.

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"There are certainly states and groups with the intent to do it, terrorist groups, for example, who have no threshold when it comes to the loss of life," he said.

In a commentary at Jihad Watch, Christine Williams wrote, "In other words, they are killing machines and destructive without boundaries."

She cited a few recent known threats from terrorists like the Islamic State.

For example, according to CNN there was the ISIS call to attack the West during the Islamic events of Ramadan.

And there was a Fox News report about a call in al-Qaida's online magazine to jihadis to assassinate business leaders and entrepreneurs.

Or, as Williams wrote, "In the words of al-Qaida leader Ayman al-Zawahiri: 'The first matter is striking the West and specifically America in its own home, and attacking their interests that are spread everywhere.'"

Finally, the broad ISIS threat from 2014 that "the best thing you can do is to strive to your best and kill any disbeliever, whether he be French, American or from any of their allies."

The commentary noted that it was most revealing that when the 2014 threat was issued, the U.K. Home Office "called the message 'propaganda' and called for Internet providers to pull it down."

"Now the director of the U.K. Government Communication Headquarters has issued his warning about terrorists having 'no threshold when it comes to life," and that at the click of a button, our cities could be crippled," the commentary continued.

In the Telegraph, Hannigan said, "We're not quite there yet, but as the world becomes ever more connected that will become a greater risk."

But the Jihad Watch article pointed out that French Interior Minister Bernard Cazeneuve said in 2014 "France is not afraid" of terrorists because it is "not the first time we have been threatened by terrorist groups that attack our values of tolerance, humanism, respect for human rights and democracy."

Since then terrorists have struck multiple times in France, including the recent multi-location assault that left some 130 people dead.

"Then there was the attack on Brussels and the catastrophic fallout from the flood of Muslim refugees into Germany. Now, at the click of a button, a major city may soon be crippled," Williams wrote.

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