The Joint Terrorism Analysis Centre, that's the independent organization which is responsible for setting the threat level on the basis of available intelligence. Has now decided to raise the national threat level from severe to critical. This means that their assessment is that further attack may be imminent. And for this period, military personnel will replace police officers on guard duties at certain protected sites, which are not accessible to the public.
And public will see more armed police on the transport network, and on our streets providing extra protection.