Robert Moore is in Philadelphia to explore the reasons behind a surge in gun violence across the whole of the US and asks whether the answer is more or less policing. Anushka Asthana is on the Turkey-Iran border where they're introducing tougher measures for those trying to cross, often in perilous conditions. Rageh Omaar is in Somaliland to visit the ancient caves of Laas Geel, which contain paintings that are thousands of years old, to find out how they are playing their part in the self-declared republic's ambitions for international recognition.