On Wednesday, President Obama announced that 80 U.S. military personnel have gone to Chad to aid officials there in a search for more than 200 missing Nigerian schoolgirls. "These personnel will support the operation of intelligence, surveillance and reconnaissance aircraft for missions over northern Nigeria and the surrounding area," Obama said in a  letter to Congress as reported by the AFP

According to NBC News, the troops will operate and protect a Predator drone involved in the search. Half of the group will operate the drone, while the other half will protect the first group. The troops will remain in Chad "until its support in resolving the kidnapping situation is no longer required," Obama added. 

The schoolgirls were kidnapped in Nigeria on April 14 by militants associated with the Islamist Boko Haram organization. The group is holding the girls hostage, demanding the release of some of their members from prison in exchange for the return of the girls. 

Here's the full text of Obama's letter to Congress, which was addressed to the Speaker of the House and the President Pro Tempore of the Senate: 

Approximately 80 U.S. Armed Forces personnel have deployed to Chad as part of the U.S. efforts to locate and support the safe return of over 200 schoolgirls who are reported to have been kidnapped in Nigeria. 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.

This action has been directed in furtherance of U.S. national security and foreign policy interests, pursuant to my constitutional authority to conduct U.S. foreign relations and as Commander in Chief and Chief Executive.

I am providing this report as part of my efforts to keep the Congress fully informed, consistent with the War Powers Resolution (Public Law 93-148). I appreciate the support of the Congress in these actions.