Ulsterisation refers to one part - "primacy of the police" - of a three-part strategy (the other two being "normalisation" and "criminalisation") of the British government during the conflict known as the Troubles. The strategy was to disengage the non-Ulster regiments of the British Army as much as possible from duties in Northern Ireland and replace them with members of the locally recruited Royal Ulster Constabulary (RUC) and Ulster Defence Regiment (UDR). The objective of this policy was to confine the effects of the conflict to Northern Ireland.
This strategy was outlined in an unpublished 1975 British strategy paper titled The Way Ahead produced by a committee of senior British Army, RUC and MI5 officers, chaired by John Bourn, a Northern Ireland Office civil servant. Under Labour’s first Secretary of State for Northern Ireland Merlyn Rees, it came to be the dominant British approach to the conflict into the 1980s.
The Rees administration aimed at putting security policy on a more logical and rational basis, and along with the Chief Constable of the RUC, Englishman Kenneth Newman they produced the often controversial strategies of "criminalisation" and Ulsterisation. These policies would later be extended by Roy Mason, and would include the use of the Special Air Service on the Irish border.
'Criminalisation' was meant to avoid any acknowledgement of the political motivation and nature of the conflict and was partly motivated to change perceptions of the conflict from a colonial war to that of a campaign against criminal gangs. Ulsterisation brought about striking changes in the casualty patterns, with military/police casualties from Northern Ireland exceeding those from Britain for the rest of the conflict, reversing the previous pattern. It was judged that the political impact in Britain of killings of British soldiers by the Provisional Irish Republican Army was greater than the deaths of local security forces members. The drop in the number of non-UDR British Army casualties helped prevent any build-up in Britain of sentiment for a withdrawal from Northern Ireland.
The move to locally based policing followed the Hunt Report, published on 3 October 1969. This recommended a complete reorganisation of the RUC, with the aim of both modernising the force and bringing it into line with the other police forces in the UK.
The name of the policy comes from a similar US strategy towards the end of the Vietnam War called "Vietnamisation".