Cameroon's army, backed up by a regional task force, has killed at least 100 members of the militant Islamist Boko Haram group and freed 900 people it had held hostage. Cameroon is part of an 8,700-strong regional task force also comprising troops from Chad, Niger, Nigeria and Benin that aims to destroy Boko Haram, which though based mainly in Nigeria has become a major threat to wider regional security. Moki Kindzeka reports from Yaounde.