Today marks the two year anniversary of the kidnapping of more than 270 Nigerian girls from their school by terror group Boko Haram. And while the hashtag #BringBackOurGirls was a viral social media sensation and helped to spread awareness of the atrocity worldwide, the global outrage has done little to get the girls back. Even though some of the girls were able to escape, more than 219 girls are still captive or have been married off as child brides.

“Neither the Nigerian government nor the rest of the world that initially echoed our agonizing chant—#BringBackOurGirls—has done what it takes to fulfill that demand,” says Oby Ezekwesili, the founder of the movement, in a Newsweek op-ed published today. “Now is the time to—without any further delay—to bring our girls back.”

Photo of the abducted girls was released in 2014.

Photo of the abducted girls released in 2014.

On the day of this anniversary, Malala Yousafzai, the school girl turned brave crusader for girls’ education, has published an open letter reminding the girls’ families that the world is still hoping for their safe return and that “These girls remain in our hearts and every corner of our work.”

Dear mothers and fathers,

I write this letter with a heavy heart, knowing you have endured another year separated from your daughters. I think of you every day since we first met two years ago – and join millions of people around the world in praying for the safety and swift return of your girls.

As I did last year, I call on President Buhari of Nigeria – and everyone who can help rescue the Chibok girls – to act now. Would a president give up the fight for his own daughter? These girls are just as precious to their families.

Parents, thank you for having the courage to send your daughters to school. My dream is that one day they will come home, finish their education and choose their futures for themselves.

I pray for the day when you can embrace your girls again.

Your sister,