The military expansion of the RSO resulted in the government of Myanmar launching a massive counter-offensive named Operation Pyi Thaya (Operation Clean and Beautiful Nation) to expel RSO insurgents along the Bangladesh–Myanmar border. In December 1991, Burmese soldiers crossed the border and accidentally attacked a Bangladeshi military outpost, causing a strain in Bangladeshi-Myanmar relations. By April 1992, more than 250,000 Rohingya civilians had been forced out of northern Rakhine State as a result of the increased military operations in the area.[3]