The U.S. Secret Service was, until last Saturday, widely seen as the world’s preeminent protective security agency. The intensity of training and range of capability it delivers to its protective mission remains unparalleled. But the near assassination of former president and GOP presidential nominee Donald Trump shatters this reputation and is a disaster for the agency. The Secret Service is facing its greatest crisis since at least the attempted assassination of President Ronald Reagan in 1981.

Protection is difficult and stressful. Secret Service officers and agents must anticipate a vast range of prospective threats. They must consider whether a political donor, campaign aide, or police officer with clearance to be near a protectee might actually be an assassin in disguise.