Doctors are closer to a test in live brains that could help diagnose chronic traumatic encephalopathy, a disease that's been linked to concussions and other repeated brain assaults.
President Trump has said U.S. forces are not on the table for potential negotiations with North Korea, but he has also complained about the cost of keeping them there.
The investigation finds the troops weren't fully prepared, the mission changed and higher-level commanders weren't properly informed. The soldiers died in an ambush by militants linked to ISIS.
The U.S. military has some 20 missions across the continent. Most are for training African armies not combat. But there are risks as U.S. troops venture into the field.
The military has completed an investigation into the ambush that killed four U.S. soldiers last October. The report has not been released, but the military is briefing families of those killed.
The U.S. relies on a threat-focused approach, when the international community should also support economic and governance development in the region, argues the ex-special forces commander for Africa.