The United States has been carrying out intelligence-gathering flights over key parts of Nigeria since late November, according to aircraft tracking data and current and former U.S. officials.
The development signals increased security cooperation between the two countries.
Reuters reported that it could not independently verify the specific type of intelligence being collected by the surveillance aircraft.
However, the reconnaissance flights over West Africa come after comments made in November by former U.S. President Donald Trump, who threatened possible military action against Nigeria.
Trump alleged that Nigeria had failed to stop attacks and harassment against Christians in the country.
