Currently 7,200 military forces serve in the US Africa Command.

A Pentagon statement said in West Africa, where many jihadist groups are active, the emphasis would shift “from tactical assistance to advising, assisting, liaising, and sharing intelligence”.

Commander Candice Tresch, a Pentagon spokeswoman, told the Reuters news agency the cuts would leave “counter-violent extremist organisation” activities largely untouched in several countries, including Somalia, Djibouti and Libya.

A US official, speaking on condition of anonymity to Reuters, said the reduction of troops would likely take place over three years and could include countries like Kenya, Cameroon and Mali.

When asked whether the reduction was a result of the attack in Niger in October 2017 in which four US troops were killed, a military official said the incident did not play a role in the decision, the Voice of America reports.

"Discussions about this shift were under way before that incident occurred," the official said.

US Defence Secretary James Mattis wants to focus resources saved in Africa for potential future conflicts with Russia and China, US media report.