According to a post on England's MI5 Security Service website:
The Joint Terrorism Analysis Centre (JTAC) has changed the UK threat level from international terrorism from SUBSTANTIAL to SEVERE. The current threat level means that the threat of a terrorist attack is considered to be highly likely.
The Home Secretary said in a statement:
"The Joint Terrorism Analysis Centre has today raised the threat to the UK from international terrorism from SUBSTANTIAL to SEVERE. This means that a terrorist attack is highly likely, but I should stress that there is no intelligence to suggest than an attack is imminent."
The Joint Terrorism Analysis Centre, or JTAC, was created as the UK's centre for the analysis and assessment of international terrorism. It was established in June 2003 and is based in the Security Service's headquarters at Thames House in London. Thames House, a Grade II listed building at the corner of Millbank and Horseferry Road in central London, overlooks Lambeth Bridge and sits a few hundred yards south of the Houses of Parliament on the north bank of the Thames. It acts in the same manner as the U.S. Department of Homeland Security operates, though one would hope with less problems.
In England there are five levels of threat:
critical - an attack is expected imminently
severe - an attack is highly likely
substantial - an attack is a strong possibility
moderate - an attack is possible but not likely
low - an attack is unlikely
England's International Threat Level has reached 'Severe' status three times prior. The ratings system was first established and published on the 1st of August 2006. At that time the Threat Level was 'Severe'. England remained at Threat Level 'Severe' until the 10th of August 2006. The rating was then raised to 'Critical' where it remained until the 14th of August when the rating returned to 'Severe' once again. The rating remained unchanged until June 30th of 2007 when it was once again raised to 'Critical' where it remained until July 4th of that same year when it was dropped once again to 'Severe'. The International Terror Threat then remained 'Severe' until July 20th of 2009. That is a period lasting over two years. On July 20th of 2009 England lowered it's International Terror Threat level to 'Substantial', the lowest level the system had ever been published at. The move today broke the run which had the Threat Level at mid grade for just over six months in England.
International Terror Threat level history
January 22, 2010 • Threat level raised to SEVERE
July 20, 2009 • Threat level lowered to SUBSTANTIAL
July 4, 2007 • Threat level lowered to SEVERE
June 30, 2007 • Threat level raised to CRITICAL
August 14, 2006 • Threat level lowered to SEVERE
August 10, 2006 • Threat level raised to CRITICAL
August 1, 2006 • Threat level: SEVERE
Help Spread 1461! Share this post with your followers on Twitter!