New York's Bill de Blasio rises to London mayor's defence

New York Mayor Bill de Blasio has weighed into a growing feud between President Donald Trump and London Mayor Sadiq Khan, over the latter's response to the London terror attack on Saturday.

"I don't understand why Donald Trump is trying to undermine a man who's trying to protect the people of London," Mr de Blasio told the BBC's Nick Bryant at a press conference on Monday.