Ibrahim Shema - Governor of Katsina State, Nigeria

A violent Islamist insurgency in northern Nigeria is threatening to destabilise Africa's most populous nation. In recent months the body count has spiked alarmingly - and now the president has imposed a state of emergency in three of Nigeria's most troubled states. Stephen Sackur speaks to Ibrahim Shema, governor of the northern state of Katsina. How does Nigeria avoid sliding into chaos?