Today, 20 July, the Joint Terrorism Analysis Centre (JTAC) changed the UK threat level from international terrorism from severe to substantial. This means that a terrorist attack is a strong possibility.
The change in the threat level to substantial does not mean the overall threat has gone away—there remains a real and serious threat against the United Kingdom and I would ask the public remain vigilant.
The decision to change the threat level is taken by JTAC independently of Ministers and is based on the very latest intelligence, considering factors such as capability, intent and timescale. Substantial continues to indicate a high level of threat; and that an attack might well occur without further warning. The threat level is kept under constant review.