Khizr Khan electrified the Democratic National Convention after speaking about his son, a Muslim-American soldier who died in the Iraq war, challenging US presidential candidate Donald Trump to read the US Constitution.

Mr Trump has called the speech a "vicious attack", but Mr Khan said the Republican candidate cannot insult Muslims, women and members of his own party and not face criticism himself.

In an interview with the BBC's Jon Sopel, the Khans say it was time to stand up to Mr Trump instead of shying away from "the call of the times".