- Chibok girls believed to be held in Sambisa Forest in northeast Nigeria
- Covered in soft sand and dense bush, Sambisa Forest is a harsh terrain littered with IEDs
- Army: "Sometimes we see children's footprints"
- More international support needed to bring girls home, says operation's commander
Maiduguri, Nigeria (CNN)As night falls, the curfew comes into effect. Nobody is allowed on the streets. Anxiety hangs in the air.