US Immigration: Views from Texas

In his first budget, US President Donald Trump has been calling for billions of US dollars for the building of the wall along the border with Mexico. BBC Newsday's Shaimaa Khalil reports live from San Antonio to explore the effect of Donald Trump's immigration policies on those trying to cross the border and those living on it.

We look at the motives behind China's ambitions to build "a great wall of iron" to protect the country against Islamist separatists in the western region of Xinjiang.

And we hear from an American archaeologist who says human beings were partly to blame for the circumstances that led the Sahara to become a desert.