T Branch MI5

Northern Ireland Counter-terrorism

T Branch of MI5 was created in 1990 with responsibility for Irish counter-terrorism (ref 1, p.772). It is also responsible for other forms of domestic terrorism (ref 1, pp.863-864).

Since 2007, MI5 has had primary responsibility for national security intelligence work in Northern Ireland (ref 6).

Investigations into Northern Ireland-related terrorism are directed from MI5’s declared headquarters in Palace Barracks, just outside Belfast (ref 7).