On 8 December 2017, the Semuliki operating base, 27 miles from the town of Beni, was engaged in a protracted attack which resulted in the deaths of 15 U.N. peacekeepers and 5 Congolese soldiers killed. 53 U.N. peacekeepers were also wounded. At least 12 of the dead U.N. peacekeepers were Tanzanians. It is suspected that the attackers were rebels of the Allied Democratic Forces (ADF). This brings the total casualties of UN forces since the mission commenced in Congo to 93.