WASHINGTON - The US military said on Friday that a fourth soldier was killed during an Oct. 4 attack in Niger, raising the death toll from an incident that has thrown a spotlight on the US counterterrorism mission in the West African nation.Reuters had learned previously that one US soldier was missing after Wednesday's operation. It withheld publication of this information at the request of the Pentagon, which maintained that its rescue and recovery effort would be jeopardized.The Pentagon disclosed on Friday that the service member's body had been located. It declined to release a name, pending notification of his family."The body of another US service member has been recovered from the area of the attack, bringing the number of US service members killed in this attack to four," Colonel Robert Manning said in a statement.No group has taken responsibility for the killings, although the United States suspects that a local branch of Islamic State was responsible.The US military on Friday published the names of the three Army Special Forces soldiers from 3rd Special Forces Group (Airborne) who were killed when their reconnaissance patrol with Nigerien forces came under fire.They were Staff Sergeant Bryan Black, 35, of Puyallup, Washington; Staff Sergeant Jeremiah Johnson, 39, of Springboro, Ohio; and Staff Sergeant Dustin Wright, 29, of Lyons, Georgia.Niger's army said the joint Nigerian-American patrol on the Mali-Niger border was ambushed by militants riding in a dozen vehicles and on about 20 motorcycles near the village of Tongo Tongo.Islamist militants form part of a regional insurgency in the poor, sparsely populated deserts of West Africa's Sahel. Jihadists have stepped up attacks on UN peacekeepers, Malian soldiers and civilian targets since being driven back in northern Mali by a French-led military intervention in 2013.Malian militant groups have expanded their reach into neighboring countries, including Niger, where a series of attacks by armed groups led the government in March to declare a state of emergency in the southwest.