United States President Donald Trump threatened to withhold federal funds for the University of California, Berkeley, after hundreds of protesters smashed shop windows, set fires and clashed with police as they forced a right-wing speaker to cancel his appearance there. The violence, which occurred two hours before far-right Breitbart News editor Milo Yiannopoulos was to give a speech at the student union on Wednesday, prompted the school to put the campus on lockdown. Mr Trump tweeted yesterday: "If U.C. Berkeley does not allow free speech and practices violence on innocent people with a different point of view - NO FEDERAL FUNDS?"