The US Government has sent 80 military personnel to Nigeria in an effort to find the schoolgirls abducted by terrorist group Boko Haram last month.
In a letter to congressional leaders, US President Barack Obama said: "These personnel will support the operation of intelligence, surveillance and reconnaissance aircraft for missions over northern Nigeria and the surrounding area.
"The force will remain in Chad until its support in resolving the kidnapping situation is no longer required."
An unnamed US military official was quoted by Reuters as saying that the flights would be carried out by an unarmed Predator drone, which are in addition to the unmanned surveillance flights already performed by the Global Hawk aircraft.
Approximately half of the newly deployed forces would be responsible for the launch and recovery of the aircraft, while the rest will provide security to the ground forces, the official added.
Meanwhile, US Department of Defense (DoD) spokesperson lieutenant colonel Myles Caggins was quoted by The Wall Street Journal as saying: "Locating this force in Chad allows us to spend more time flying over the search area."
The deployment adds to the interagency team comprising individuals from the US State Department, the Federal Bureau of Investigation (FBI) and the US Africa Command (AFRICOM), which was sent by the Pentagon to Nigeria earlier this month.
The US Department of Defense (DoD) has been flying unmanned surveillance flights over the dense forested regions of north-east Nigeria for almost two weeks, and also signed an agreement to share of intelligence data with the Nigerian Government.
After kidnapping more than 200 teenage girls from their secondary school in Chibok, north-eastern Nigeria, Boko Haram has since threatened to sell them into slavery if the government fails to release the group's imprisoned militants.