Ulsterisation refers to one part 'primacy of the police' of a three part strategy by the British Government to pacify Northern Ireland 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 security duties in Northern Ireland and replace them with members of the locally recruited Royal Ulster Constabulary and Ulster Defence Regiment. The objective of this policy was to confine 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This strategy was outlined in an unpublished 1975 British strategy paper titled "The Way Ahead" produced by a committee of senior Army, RUC and intelligence officers, chaired by John Bourn, a Northern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 theme in the conflict as it raged 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 strategy of 'criminalisation' and 'Ulsterisation.' These policies would later be extended by Roy Mason, and would include the employment of the Special Air Service on the Irish border.
'Criminalisation' was meant to avoid any acknowledgement of 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. It was judged that the political impact 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 regular 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".