This is the backdrop against which a series of difficult questions emerges. There is deep confusion over exactly what went wrong, including why U.S. troops were traveling in unarmored vehicles, how Johnson was separated from the group, how he died, and why it took so long to find him. As public scrutiny of the incident intensifies, so too do the many stories about what may have taken place. On social platforms like Twitter, people are sharing graphic details about the troops’ final, brutal hours. But there’s little clarity, and certainly sparse information from public officials about what actually happened.

An offshoot of the Islamic State has been named as a potential suspect in the attack, during which roughly 50 terrorists are believed to have assaulted the troops with grenades and machine guns. The Pentagon launched its own investigation into how the attack took place and why its troops—who were on a joint patrol with troops from Niger—were so unprepared for it. The FBI announced that it would launch its own investigation. Speaking on background, one intelligence expert said the presence of the FBI indicates that the servicemen were not in a combat situation, and that their deaths are being treated as a terrorism case.

The incident seems certain to make it harder for President Donald Trump to avoid discussing U.S. military engagement in Africa, a little-talked-about keystone in the global U.S. war on terrorism. It took the president 12 days to publicly acknowledge the deaths of the four U.S. troops, which he did only after a journalist pressed him on the issue.

The U.S. military has been training soldiers from Niger since the early 2000s. Their aim has largely been to improve the country’s military capacity—to turn them into a force that can not only handle threats like terrorism on its own, but can also eventually train itself. But in recent years, the U.S. footprint in Niger has grown, mainly to meet the threat of extremists spilling into the country from neighboring Mali and Nigeria.

U.S. Africa Command spokesperson Patrick Barnes said in a phone call that the military relationship with Niger grew from trainings to regular rotations of U.S. troops in 2011, as well as “accompanying and assisting” instead of just running short-lived trainings. Now, there are roughly 800 U.S. servicemen and women assigned to Niger, including some special forces. In the northern town of Agadez, for example, Barnes said there are “a few hundred Air Force” personnel, and other Americans assisting in surveillance out of the capital of Niamey. As for this latest incident, he said AFRICOM is “going to let the investigation run its course.”

“In the process of doing that, we'll see if there are things we could have done differently that will help us going forward,” Barnes said.