The South Sudanese army now admits it shot down in error a UN helicopter killing its four Russian crew members.
The UN says it was on a reconnaisance mission in an area where the SPLA has been fighting Yau Yau rebels.
The army says it saw the Mi8 helicopter landing and contacted the UN mission, UNMISS, to find out if it had flights in the area. When told there were none, it opened fire.
UNMISS has been operating in South Sudan since the July 2011 creation of the country, and since that September has reported six incidents of its planes being fired on, searched, threatened or detained. Russia has already stood down
its UN air support group, some 120 people, after voicing safety concerns, and says it will pull out next March.
Four UN troops also lost their lives in a separate incident in the western Darfur region in a friendly fire incident.