US forces have lost an unarmed drone aircraft over Libya, the Pentagon announced Friday.
"An unarmed US Africa Command remotely piloted aircraft (RPA) was lost over Tripoli, Libya" on Thursday, the command said in a statement.
No reason was given for the loss, and the Africa Command said it was under investigation.
The command conducts drone operations in Libya "to assess the ongoing security situation and monitor violent extremist activity," it said.
"These operations are critical to counter terror activity in Libya and are fully coordinated with appropriate government officials."
The US drone loss came a day after the Libyan National Army led by Khalifa Haftar said it shot down an Italian drone in western Libya, flying in a zone under its control.
In September, the US military said it carried out several airstrikes against the ISIS group in Libya, killing more than 40 militants. Those were the first US strikes in the North African country in over a year.
Oil-rich Libya descended into chaos in 2011, when an international military coalition helped rebels overthrow longtime autocrat Moammar Gadhafi. Extremists have exploited the chaos to expand their reach in the country.