The US is cutting hundreds of troops in Africa as it focuses on countering threats from Russia and China.
Around 700 counter-terrorism troops will be removed over the next few years, the Department of Defense said.
About 7,200 US soldiers are currently based in dozens of African countries including Nigeria and Libya.
There will now be a shift away from tactical assistance to advising and sharing intelligence in West Africa, the Pentagon said.
However, counter-terrorism activities in several countries including Somalia and Djibouti will remain largely the same.
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 such as Kenya, Cameroon and Mali.
Pentagon spokeswoman Candice Tresch said: "We will realign our counter-terrorism resources and forces operating in Africa over the next several years in order to maintain a competitive posture worldwide."
A military official said an attack in Niger in October 2017 in which four US troops were killed did not play a role in the decision to cut troops, the Voice of America reports.
The move comes as US President Donald Trump works to implement his National Defense Strategy, which ushers in a new era of "Great Power competition" with Moscow and Beijing.
On Wednesday, a bipartisan congressional panel reviewing the strategy said America's focus on counter-insurgency operations had weakened its military capability.
Why is the US cutting troops in Africa?
By Tomi Oladipo, BBC Africa Security Correspondent
The announcement of cuts has been coming for some time.
In January, the US Defence Secretary James Mattis unveiled a new strategy indicating a shift away from terrorism and towards America's standing when compared to Russia and China.
While the cuts begin in Africa, they will eventually affect US military personnel elsewhere. The funding will now be put into military muscle-flexing, as Beijing and Moscow embark on renewed global ambitions.
The Pentagon will feel it has been successful in training partner forces in Africa and setting them up to competently fight insurgent groups - particularly Islamist extremists.
An example is in Cameroon, where the US feels local Special Forces are now able to operate independently.
Even though the US has spent years growing a secret military footprint across Africa, it will only keep those that are most essential, and focus on areas where there is a security vacuum, such as Libya and Somalia.