MI5 downgrades terrorism threat from Northern Ireland The threat level to Northern Ireland from Northern Ireland-related terrorism remains at severe, meaning that an attack is highly likely. Neither of these two levels has changed. Despite the change which has been made today, there remains a real and serious threat against the United Kingdom from terrorism and I would ask the public to remain vigilant and to report any suspicious activity to the police. The decision to change this threat level is taken by the Security Service independently of ministers and is based on the very latest intelligence, considering factors such as capability, intent and timescale. Threat levels are kept under constant review. The threat assessment was increased in September 2010 after Jonathan Evans, the director-general of MI5, warned that dissident Irish republicans could attempt a new wave of terrorist attacks on the British mainland. The Security Service has published the threat level to the UK online since 2006.