The Counter Terrorism Command (SO15) is responsible for countering the threat from terrorism and related activity on behalf of the MPS. This involves a range of operational activity, including proactive intelligence-led operations and reactive investigations, support to the intelligence services in gathering and assessing intelligence, and engagement with a range of partners to prevent terrorist related activity. Matching the threat faced, the Command operates against the threat of terrorism at local, national, and international levels. In addition to this core counter-terrorism function the Command undertakes a number of other vital national security functions. It has the national lead for domestic extremism, a role undertaken by the National Domestic Extremism Unit.