The US has been conducting intelligence-gathering flights over large parts of Nigeria since late November, according to flight tracking data and current and former US officials, in a sign of increased security cooperation between the countries.
Reuters could not determine what information the flights are meant to obtain.
But the flights in West Africa follow US President Donald Trump's threats in November to militarily intervene in Nigeria over what he says is its failure to stop Christian persecution.
The US contractor-operated aircraft used for the surveillance operations typically takes off from Ghana and flies over Nigeria before returning to Accra, the Ghanaian capital, the tracking data for December shows.
Surveillance flights
Flight tracking data shows the operator is Mississippi-based Tenax Aerospace, which provides special mission aircraft and works closely with the US military, according to the company's website. Tenax Aerospace did not respond to a request for comment.
Liam Karr, the Africa Team Lead for the Critical Threats Project at the American Enterprise Institute, has analysed the flight data. He said the operation appeared to be running out of an airport in Accra, a hub for the US military's logistics network in Africa.
Karr said the operation was an early sign the US was rebuilding its capacity in the region after Niger ordered US troops to leave a sprawling, newly built air base in the country last year.
"In recent weeks we've seen a resumption of intelligence and surveillance flights in Nigeria," Karr said in an interview.
'Productive meetings'
A former US official said the aircraft is among several assets the Trump administration moved to Ghana in November. It is unclear how many aircraft remain in Ghana.
A current US official confirmed the aircraft has been flying over Nigeria but declined to provide details given the diplomatic sensitivity of the issue.
In a statement, the Pentagon said the US government held productive meetings with Nigeria following Trump's message about the country, but declined to discuss intelligence matters.
Nigeria's military spokesperson did not respond to requests for comment. Ghana's deputy defence minister also did not respond to a request for comment.
Flown to Nigeria nearly daily
A Nigerian security source, speaking on condition of anonymity, said the US agreed in a November 20 meeting between Nigerian National Security Advisor Nuhu Ribadu and US Defence Secretary Pete Hegseth to deploy air assets to gather intelligence. A spokesperson for the Nigerian military did not respond to requests for comment.
The Tenax Aerospace aircraft was seen on November 7 by flight tracking data at MacDill Air Force Base, which is home to the headquarters of the United States Special Operations Command in Tampa, Florida.
It flew to Ghana on November 24, just days after the high-level meeting between US and Nigerian security officials, according to flight tracking data.
The data shows the aircraft has flown over Nigeria almost daily since the start of the operation. The aircraft is a Gulfstream V, a long-range business jet often modified for intelligence, surveillance and reconnaissance missions, according to the data.
Security emergency
Nigeria's President Bola Tinubu declared a security emergency last month and ordered the army and police to begin mass recruitment to tackle worsening armed violence across the country.
That move followed attacks in multiple Nigerian states where civilians were killed and kidnapped, and the mass abduction of more than 300 schoolchildren in northern Nigeria.
The US and Nigeria have established a joint task force to work on security, according to Republican US Representative Riley Moore, who recently travelled to the West African country.
