sentences:  "M23 fighters patrolled the streets of Congo’s main cities, firing on or arresting protesters or anyone else deemed to be a threat to the president," they said.Fierce fighting has erupted in Masisi between government forces and a powerful local warlord, General Delta.The United Nations mission in the DRC is its largest and most expensive peacekeeping effort, but it shut down five UN bases near Masisi in 2017, after the US led a push to cut costs.