The UK’s terrorism threat level has been upgraded from “substantial” to “severe”.
The move means security chiefs believe that an attack is highly likely but there is no specific intelligence of an imminent incident.
The move follows Monday night’s shooting in Vienna in which four people died.
Last week, three others died in a knife attack in Nice, France, and a teacher was murdered in Paris last month.
Home Secretary Priti Patel tweeted it was “a precautionary measure and is not based on any specific threat”.
“The public should continue to remain vigilant and report any suspicious activity to the police,” she added.
Assessments of threat levels are taken by the Joint Terrorism Analysis Centre (JTAC), part of MI5, which makes its recommendations independently from the government.
The five levels of threat set by the JTAC are:
- Low – an attack is highly unlikely
- Moderate – an attack is possible but not likely
- Substantial – an attack is likely
- Severe – an attack is highly likely
- Critical – an attack is highly likely in the near future
The UK’s terrorism threat level was raised to the highest rating, “critical”, in the days following the Manchester Arena bombing in May 2017.
It last reached that level again briefly in September that year, after a bomb partially exploded on a Tube train at Parsons Green.
The threat level remained at the second highest rating, “severe”, until last November when it was downgraded to “substantial”, where it has stayed until now.