CONGO'S government blamed M23 rebels for an attack on a helicopter that killed a United Nations peacekeeper, as hundreds in the eastern city of Goma demonstrated over spiralling insecurity in the region. Militia violence has racked the Democratic Republic of Congo's vast mineral-rich east for two decades despite local and regional military interventions and U.N. peacekeeping efforts. A helicopter operated by the peacekeeping force MONUSCO came under fire on Sunday after taking off from the city of Beni. A South African peacekeeper was killed and another wounded. Neither South Africa nor MONUSCO said who might be responsible, nor what kind of weapon…