The United States earlier this month withdrew most of its troops deployed for a joint counterterrorism operation in northeastern Nigeria.

The area has long been a hotbed for the Boko Haram Islamist militant group and its splinter factions — particularly the Islamic State West African Province (ISWAP), one of "Islamic State"'s most active affiliates globally.

US Africa Command's General Dagvin Anderson described the joint operation as a model for future security cooperation on the continent.

"We have withdrawn much of our forces that were just there for that operation," Anderson told reporters at a conference of African defense chiefs in Luanda, Angola.

"But [we] are continuing the partnership that Nigeria has asked for to help continue with the intelligence sharing and the understanding that's necessary to be able to prosecute these difficult tasks," he said.US troops were deployed alongside Nigerian forces (pictured) in an operation against IS fightersImage: Reuters