Nigerian president Muhammadu Buhari told the 21 Chibok girls rescued this week that he will redouble efforts to find those still missing two years after their kidnapping.

“We shall redouble our efforts to bring the rest back home,” Buhari said Wednesday. “Aside from rescuing them, we are assuming the responsibility for their personal, educational and professional goals and ambitions in life. It is not late for the girls to go back to school and continue the pursuit of their studies.”

Nearly 300 girls were taken from their school in 2014 in Chibok in northeastern Borno state, where Boko Haram has waged a seven-year insurgency aimed at creating an Islamic state, killing thousands and displacing more than 2 million people.

Last week, the rebels released 21 girls in the first negotiated release brokered by the International Red Cross and the Swiss government.

Boko Haram controlled a large portion of Nigeria at the start of 2015, but Nigeria’s army, aided by troops from neighboring countries, has recaptured most of that territory.