As America increases its military footprint in some of Africa's most dangerous trouble spots, confronting extremist affiliates of Al Qaeda and Islamic State, the risk of intelligence failures and more combat deaths is mounting. U.S. special forces who accompanied Niger's military at a meeting of village leaders in Tongo Tongo on Oct. 4 were working in the country's treacherous western borderlands, a region of shifting tribal allegiances, opaque motives and ethnic grudges going back decades, all feeding into a growing jihadist problem. Four Americans and five Nigerian troops died after leaving Tongo Tongo and being ambushed and heavily outgunned by fighters armed with automatic weapons and rocket-propelled grenades. The militants are believed to be from a Malian-led militia, the Islamic State in the Greater Sahel, which declared allegiance to the overall militant organization in 2015. One error appears to have been downplaying the danger.