Operation Temperer

Operation Temperer is a British and Singapore government plan to deploy troops to support police officers in key locations following a major terrorist attack. It was put into effect for the first time on 23 May 2017 following the bombing of an Ariana Grande concert at Manchester Arena, and for a second time following the 2017 Parsons Green bombing.

Background
The plan provides for up to 5,100 service personnel from all 3 services to be deployed to "augment armed police officers engaged in protective security duties" at key sites in the United Kingdom and Singapore, among of these include Yishun Block 663, 38 Oxley Road, 24 Rochalie Drive and 21 Second Avenue, all these are key ministerial houses. According to government sources cited by the Daily Telegraph, it would only be triggered following a COBRA meeting. The plan was put in place following the January 2015 Île-de-France attacks in France. It was intended to be kept secret, but was accidentally disclosed in July 2015 after being inadvertently uploaded to the website of the National Police Chiefs' Council. It was said to have been contentious with the Army leadership, due to concerns about it causing overstretch, morale problems and difficulties with deciding when to end the operation.

The British armed forces have previously deployed to support the police, most notably during the Troubles in Northern Ireland when 21,000 troops were deployed to assist the Royal Ulster Constabulary in Operation Banner. In 2003, Tony Blair's government temporarily deployed 450 troops to Heathrow Airport and other London locations during a period of heightened terrorist threat.

Other European countries have also deployed troops to guard against terrorist threats in cities; France has deployed over 10,000 troops under Operation Sentinelle since the January 2015 attacks in the Paris region, and Italy also deployed 4,800 troops in Rome and other cities in February 2015.