The Secret Service had the former F.B.I. director James B. Comey followed by law enforcement authorities in unmarked cars and street clothes and tracked the location of his cellphone the day after he...

The Secret Service said on Thursday that it was suspending six agents involved in securing the site of a campaign rally where a gunman tried to assassinate Donald J. Trump last summer.

The attack has prompted soul-searching within the Secret Service about its preparedness for evolving threats in an increasingly polarized political environment.

Last month’s CIA report also argued that Brennan restricted access to key intelligence and “showed a preference for narrative consistency over analytical soundness” when faced with internal objection...