Rising tensions after the deadly ambush of police officers in Dallas have prompted officials in Cleveland and Philadelphia to adjust security plans for this month's national political conventions.
Cleveland Police Chief Calvin Williams says his department has "ramped up" its security plans for the GOP convention and moved up by a week the activation of a tip line for reporting suspicious activity.
Philadelphia Police Commissioner Richard Ross says the fatal shooting of five Dallas police officers last week will require that police take a different tactical approach, although he would not elaborate.
The Republican National Convention begins yesterday in Cleveland and the Democratic convention on July 25.
