The terror threat level in the United Kingdom was raised by government officials on Tuesday from “substantial” to “severe,” after the terror attack in Vienna Monday night that killed four people, as well as the string of recent deadly attacks in France. 

Home Secretary Priti Patel said the British people should be alert but not alarmed. 

“This is a precautionary measure following the horrific events of the last week in France and last night in Austria and is not based on a specific threat,” she said. 

Sky News reports the decision to raise the country’s threat level was done by the Joint Terrorism Analysis Centre (JTAC).  The JTAC is located at MI5’s London headquarters and consists of counter-terrorism experts from the police, government, and security agencies. 

A UK security source told Sky News’ defense and security correspondent Alistair Bunkall that there was no specific threat to the UK but recent attacks in Europe felt “different in tactic and tempo”, and the raised threat level is a response to that.

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The source added the UK has been operating at the top of “substantial” for some time and it wasn’t going to take much to nudge the country into the “severe” category, with Vienna being that nudge.

The JTAC had unexpectedly lowered the national threat level to substantial last November, following the death of the ISIS leader, Abu Bakr al-Baghdadi; prior to that, it had been at severe or even higher since August 2014, according to The Guardian

The newspaper reported that over the last few days, Muslim propagandists have used social media to focus on France after President Emmanuel Macron vigorously defended his country’s secularism following several attacks that began when a teacher showed cartoons of the prophet Muhammad to his class.

Intelligence sources told the Guardian it was unclear if the attacks in Austria were timed to be carried out on the night before the start of a lockdown when more people would have been out in the evening on the streets. 

The UK will begin its lockdown just after midnight on Thursday. 

Last month, MI5’s new director-general Ken McCallum said the security service had disrupted “27 late-stage terrorist attack plots in Great Britain,” of which the majority were Islamist extremists.