U.S. Detected Potential Iranian Plot to Kill Trump Separate From Saturday’s Shooting

U.S. intelligence agencies were tracking a potential Iranian assassination plot against former President Donald J. Trump in the weeks before a gunman opened fire last weekend, several officials said on Tuesday, but they added that they did not consider the threat related to the shooting that wounded Mr. Trump.

The intelligence prompted the Secret Service to enhance security for the former president before his outdoor campaign rally in Butler, Pa., on Saturday, officials said. Yet whatever additional measures were taken did not stop a 20-year-old local man from clambering on top of a nearby warehouse roof to shoot at Mr. Trump, grazing his right ear and coming close to killing him.

The National Security Council contacted the Secret Service to be sure it was tracking the latest reporting and the agency shared the information with the head of Mr. Trump’s detail, according to a national security official, who like others shared sensitive information on condition of anonymity.

The Trump campaign was told about the Iranian threat not long before Saturday’s shooting, according to two people briefed on the situation, although it was not clear whether the former president himself was informed.

The intelligence that prompted the warning was new, but consistent with previous threat information, according to U.S. officials. The intensifying campaign season, with increasing public rallies, offered more opportunities for an attack. One national security official said that although the threat was taken seriously, it did not appear from the intelligence to be fully developed.

While several officials said the Secret Service had surged additional “resources and assets,” they declined to describe specifically what changes had been made. The