Three USA green berets killed in a clash on the Niger-Mali border, where Islamic State fighters have established a presence, officials said Thursday.A joint US-Niger patrol fell into an ambush on Wednesday in the Tillaberi region in the country's southwest, requiring French Mirage 2000 fighter jets to be air support. Another person from an unnamed country was also killed, according to the Pentagon statement.Niger's President Mahamadou Issoufou said there were many casualties in the battle, and US Africa Command said two more Special Forces troops were wounded. The fatal "ambush" also wounded eight Nigerien troops, a statement from Niger's defence ministry said. "Our country has just been attacked once more by terrorist groups, an assault which sadly has resulted in a large number of casualties," Issoufou said in the capital Niamey. A French military spokesman said French helicopters had evacuated wounded from the scene and added that the fig...