Inadequate communication, unguarded warehouses, and a lack of written instructions have emerged as key factors contributing to the U.S. Secret Service's failure to protect former President Donald J. Trump from an assassination attempt at a campaign rally in Butler, Pa. on July 13, according to a recent investigation by The New York Times.

The Secret Service's shortcomings at the Butler Farm Show grounds, where a gunman fired shots that grazed Mr. Trump's ear, injured two attendees, and tragically took another life, are expected to be outlined in an internal assessment conducted by the Secret Service itself. Additionally, an independent Senate investigation is set to release its own report on the incident.

The urgency to address these failures has been highlighted by the recent identification of another attempted attack on Mr. Trump's life at his golf course in West Palm Beach, Fla., as reported by the FBI. Senator Richard Blumenthal, Chairman of a Senate subcommittee investigating the security lapses in Butler, stated that the incident on July 13 was preventable, and some of the lapses were "so egregious as to be almost unbelievable."

Through interviews with federal, state, and local officials, as well as a review of documents, a picture emerges of how planning oversights left vulnerabilities that allowed a 20-year-old individual to open fire on Mr. Trump. One major flaw was the breakdown in communication between the Secret Service and the local law enforcement agencies involved in securing the rally. Of particular concern were unguarded warehouses owned by AGR International, located near the rally site, where the assailant climbed onto the roof to target Mr. Trump.

Records of discussions between the Secret Service and local law enforcement officials reveal that the risk posed by the unsecured warehouses was acknowledged but not adequately addressed. During a walk-through the day before the rally, the Secret Service was still considering ways to prevent public access to the warehouses, such as adding police patrols or parking farm equipment nearby. Despite these discussions, the warehouses were ultimately left unguarded on the day of the event.

The deficient communication between the Secret Service and local law enforcement agencies was not the agency's only misstep. Security plans for the rally were not effectively communicated to their partners, leading to confusion and officers improvising their duties. Compounding the situation, essential personnel responsible for Mr. Trump's protection were not present in the Secret Service's command center, resulting in a delayed realization that the assailant was armed.

The Secret Service declined to provide specific answers regarding the security planning, while acknowledging their full responsibility for the failures in Butler. Acting Director Ronald L. Rowe, Jr. recently briefed members of U.S. House and Senate committees on the agency's ongoing investigation into the attempted assassination of Mr. Trump.

The failure to address security gaps from the initial planning stages to the actual event was a critical oversight by the Secret Service. Former members of the agency emphasize the importance of ensuring proper staffing and addressing any unattended areas to maintain optimum security during such events.

Securing the Butler rally was already a challenging task, as the Secret Service often faces resource constraints during election years. Additionally, the presence of Jill Biden, the first lady, attending a nearby dinner at the same time as Mr. Trump's event, placed additional demands on the field office responsible for their protection.

Former presidents typically receive a lower level of protection compared to sitting presidents and their families as per longstanding policy. However, Mr. Trump's protective detail was noted to be the largest ever provided to a former president, demonstrating a higher level of security compared to previous administrations.

Planning for public events, though complex, is typically a meticulous process. The Secret Service assesses vulnerabilities, assigns security details, develops transportation plans, and coordinates with local law enforcement agencies and state police. At least 10 agencies were involved in securing the Butler Farm Show grounds for the Trump rally.

The investigation into the security failures highlights the need for better coordination, communication, and implementation of protective measures to prevent such incidents in the future. The Secret Service's internal assessment, along with the findings of the independent Senate investigation, will shed further light on the gaps and areas that need improvement in protecting high-profile individuals during public events.