The British government.
Ted Heath Jan 1972 “As to Londonderry, a military operation to reimpose law and order would be a major operation necesarily involving numerous civilian casualties”.
General Robert Ford Jan 1972 “I am coming to the conclusion that the minimum force necessary is to shoot selected ringleaders among the Derry young hooligans after clear warnings have been given”.
Cause and effect. British troops were never acceptable on Irish soil, the scum British government knew this and still went ahead with the inevitable outcome of Bloody Sunday and Ballymurphy.