Armed police
Media playback is unsupported on your device
Video

Why has the terror level changed?

BBC Security Correspondent Frank Gardner assesses the terror threat to the UK and why it has been changed to severe.

The level has been raised in response to conflicts in Iraq and Syria, Home Secretary Theresa May has said.

  • 29 Aug
  • From the section UK
Go to next video: UK threat level rise 'justified'