At least 41 people have been killed in a suicide car bombing in Pakistan’s Swat valley, officials say. The explosion hit a security convoy in Shangla district � an area the military said it had retaken from militants. It is the latest in a string of attacks and comes amid warnings of an offensive against militants in nearby South Waziristan, on the Afghan border. Marco Werman speaks with the BBC’s Aleem MaqBool in Islamabad.