US Africa Command (AFRICOM) said most American troops deployed for a recent operation against Islamic State militants in Nigeria have now withdrawn, while Washington continues to support Abuja through intelligence sharing.

Speaking after a meeting of African defense chiefs in Luanda, Angola, AFRICOM Commander General Dagvin Anderson said the temporary deployment had achieved its objective.

The joint operation in May killed Abu-Bilal al-Minuki, identified by the US military as the Islamic State group's second-highest-ranking leader globally. It followed a US strike on Christmas Day ordered by President Donald Trump.

"We have withdrawn much of our forces that were just there for that operation, but are continuing the partnership that Nigeria has asked for to help continue with the intelligence sharing," Anderson told journalists during a US State Department-hosted briefing after the conference.

Anderson said the mission reflected Washington's approach to security cooperation in Africa, combining specialized capabilities with partner-led operations.

The operation in the Lake Chad Basin significantly weakened Islamic State leadership and disrupted its communications and wider network, with effects extending beyond West Africa due to the group's international links, he said.

"Nigeria has been very active since that operation in May," Anderson said. "They continue to prosecute targets themselves."

He added that continued pressure from Nigerian forces, alongside publicizing the results of the operation, had contributed to more defections and surrenders among ISIS fighters in northeastern Nigeria.