US politicians are voicing concern over America's growing military presence across Africa, where they worry the Pentagon is getting ever more embroiled in a secretive campaign against a shifting enemy.
Last month's killing of four US soldiers in a Niger ambush has thrust the issue into the spotlight, with lawmakers calling for greater transparency on what is going on in Africa.
"The footprint in Africa is much bigger than the American public understands," Democratic Senator Tim Kaine said this week.
The Niger ambush has also rekindled debate over the legal authorities the Pentagon uses to fight jihadist groups overseas, particularly in Africa where about 6,000 US troops are deployed across the vast continent.
Defense Secretary Jim Mattis this week faced lawmakers' questions on these war fighting powers. They were initially passed three days after the September 11, 2001 attacks on New York and Washington to go after Al-Qaeda but have since been used to hunt Islamists from a variety of other groups.
US lawmakers are considering updating or repealing this Authorization for the Use of Military Force (AUMF), but Mattis and Secretary of State Rex Tillerson do not think it should be changed or repealed, unless a replacement is ready to go.
"I'm not sure that Congress envisioned that we would have the potential of ground troops in Northern Africa in combat missions," Democratic Senator Ben Cardin said.
Mattis said Al-Qaeda has morphed into various offshoots, including the Islamic State group, so the AUMF still applies.
"These groups come apart, go back together, they change their names as often as a rock-and-roll band," Mattis told lawmakers.
"The tragedy in Niger, the loss of four American soldiers, helped focus us on the fact that we've got citizens and we've got senators who are unclear on exactly where in the world we are engaged against this morphing, changing enemy in a new era of skirmishes," Democratic Senator Chris Coons said.
The United States this week pledged $60 million to support the new "G5 Sahel" regional counter-terrorism force.
Members of the G5, Burkina Faso, Chad, Mali, Mauritania and Niger, are viewed by the US as regional partners.
Officially, the Pentagon's missions across Africa are primarily to "train, advise and assist" African militaries to help nations stand up to various Islamist groups.
But in reality, as demonstrated in Niger, the US role sometimes goes beyond this.
According to information from the White House to Congress in June, combat-ready US troops are deployed in 19 countries - 11 of them in Africa: Somalia, Libya, Kenya, Niger, Cameroon, Uganda, South Sudan, the Democratic Republic of Congo, the Central African Republic, Djibouti and Egypt.
For Republican Senator Rand Paul, the official training mission is euphemistic fudge concealing what's really going on.
"It sounds like you got a conflict going on there. You've got conflict going on in Niger. We have 6,000 troops in 54 countries in Africa," Paul told Mattis.
According to the Pentagon, the Niger incident unfolded in early October, as a US-Niger team made a routine reconnaissance patrol in the village of Tongo Tongo near the Niger-Mali border. They were attacked by about 50 local fighters associated with the Islamic State group.
It is reported that the mission changed and they were actually trying to capture or kill a jihadist leader linked to IS and Al-Qaeda.