Saudi Arabia has removed Muhammad bin Nayef as the crown prince and replaced him with defence minister Mohammed bin Salman in a dramatic changeover in the ultra-conservative kingdom's royal family. Salman, 31, son of King Salman bin Abdulaziz, was previously the country's deputy crown prince. Nayef, the king's nephew and a familiar face in Washington, was overseeing Saudi Arabia's powerful interior ministry in charge of the security affairs of the kingdom. He has now been removed from all his official posts.