There's minerals in them thar deserts

The natural resources of Niger include uranium, coal, gold, iron ore, tin, phosphates, petroleum, molybdenum, salt, and gypsum. Niger has some of the largest uranium reserves in the world. It also has a good amount of oil reserves.

  AZO Mining: "Niger: Mining, Minerals and Fuel Resources"

That may be all you're missing in this story.

Many Americans were surprised to learn this month that American troops are deployed to Niger at all, let alone so many of them — 800 at the time of the attack, according to the Pentagon.

But U.S. troops have been in Niger in increasing numbers since at least 2013, with part-time deployments for years before that, working with the Nigerien military as it fights insurgent and terrorist groups, and using the country to spy over other countries in the Sahel and Sahara regions of the vast continent.

[...]

Defense Secretary James Mattis told reporters Thursday [...] “Their job is to help the people in the region learn how to defend themselves."

  Politico

Sure.

Hundreds of Air Force personnel operate drones and other spy flights out of a growing American base in the country, and a smaller number of special operations troops train and advise Nigerien troops as they fight Islamist extremists.

[...]

"Africa Command is establishing a temporary, expeditionary contingency support location in Agadez, Niger."

But it doesn’t capture the whole picture.

For instance, the U.S. flies surveillance missions from Niger, which is twice the size of Texas, all over northern and western Africa — including over Libya, where the United States is conducting some of its most sensitive counterterrorism operations.

Part of the reason U.S. advisers were deployed to Niger in the first place was as a "quid pro quo" for allowing Washington to locate a regional surveillance hub there.

[...]

A military spokesman said on Oct. 6 that an unarmed surveillance aircraft was overhead during the mission [in which four American Green Berets were killed] — although NBC News, citing a congressional source, reported otherwise on Friday — but didn’t spot the attackers before the ambush.

Let's see - a military spokesman vs. a congressional source. Tossup? At any rate, somebody's trying to hide something there.

 ...but hey, do what you want...you will anyway.