The video released Monday by Islamic militant group Boko Haram was confirmed to be authentic by the US, according to State Department Spokesperson Jen Psaki.
"Our intelligence experts are combing through every detail of the video for clues that might help ongoing efforts to secure the release of the girls," kidnapped by Boko Haram, Psaki told reporters.
The video shows a large group of the girls who were kidnapped four weeks ago wearing abayas and sitting behind the group's leader Abubakar Shekau in a rural location.
Boko Haram offered to trade some of the schoolgirls they kidnapped in exchange for prisoners.
Psaki indicated the offer is for Nigeria to decide but stressed, "the United States' policy, I should say, is to deny kidnappers the benefits of their criminal acts, including ransoms or concessions