Buhari told parents of the missing students that he goes to bed and wakes up every day "with the Chibok girls on my mind."
The president announced the investigation yesterday, telling parents it will seek to unravel the circumstances that led to the April 15, 2014 kidnapping and the actions and inactions that followed, according to a statement.
Gen Gabriel Olonisakin, the chief of defense staff, accompanied the president and told the parents that the military has the ability to rescue the Chibok girls but "intelligence is delicate and we don't want to do anything to jeopardise the lives of the girls."
Some 276 girls were kidnapped from a government boarding school in the remote northeastern town of Chibok. Dozens escaped on their own but 219 remain missing.
The abduction brought international attention to Nigeria's home-grown extremists and the failures of then-President Goodluck Jonathan and his military to rescue the girls.