Washington (AP) — A threat on Donald Trump’s life from Iran prompted additional security in the days before Saturday’s campaign rally, but it was unrelated to the assassination attempt on the Republican presidential nominee, two U.S. officials said Tuesday, as law enforcement warned of the potential for more violence inspired by the shooting.

National Security Council spokesperson Adrienne Watson said officials have been tracking Iranian threats against Trump administration officials for years, dating back to the last administration. Trump ordered the 2020 killing of Qassem Soleimani, who led the Iranian Islamic Revolutionary Guard Corps’ Quds Force.

“These threats arise from Iran’s desire to seek revenge for the killing of Qassem Soleimani. We consider this a national and homeland security matter of the highest priority,” Watson said.

The U.S. Secret Service and the Trump campaign were made aware of the latest threat, prompting a surge in resources and assets, according to the officials, who spoke on the condition of anonymity to discuss sensitive intelligence matters.

The additional resources did not prevent Saturday attack at a rally in Pennsylvania, where a 20-year-old with an AR-style rifle opened fire from a nearby rooftop, leaving the former president with an ear injury, killing one rallygoer and severely injuring two others.

Watson said there have been no ties identified between the gunman at the rally “and any accomplice or co-conspirator, foreign or domestic.”

“The Secret Service and other agencies are constantly receiving new potential threat information and taking action to adjust resources, as needed,” said Secret Service spokesman Anthony Guglielmi who said he couldn’t comment on any specific threats.

Online rhetoric is particularly concerning Since the rally shooting, rhetoric online has become particularly concerning “given that individuals in some online communities have threatened, encouraged, or referenced acts of violence in response to the attempted assassination,” according to a joint intelligence bulletin by Homeland Security and the FBI.

Presidents — and presidential candidates — are always the subject of threats, but the FBI and Homeland Security officials are “concerned about the potential for follow-on or retaliatory acts of violence following this attack,” according to the bulletin released Monday evening. Law enforcement warned that lone actors and small groups will “continue to see rallies and campaign events as attractive targets.”

A visibly stronger security detail now surrounds Trump and President Joe Biden. And independent candidate Robert F. Kennedy Jr. received Secret Service protection in the wake of the shooting.

There were more agents surrounding Biden as he boarded Air Force One to Las Vegas on Monday night. As Trump made his first post-shooting appearance on the floor of the Republican National Convention in Milwaukee that same night, there was a much larger presence than he has previously had, with agents keeping a protective barrier between Trump and the crowd, preventing him from greeting supporters as easily as he usually does.

Show of force, but also an effort to reassure Both Trump and Biden have called for unity following the shooting; Biden has said repeatedly that political violence must be rejected.

The FBI has no clear motive for the shooting and the investigation is ongoing. Biden ordered an independent review of the federal response after questions swirled about how the gunman could have gotten so close to the stage, and how the enhanced security presence did not prevent the attack. Security will also be enhanced at the Democratic National Convention in Chicago in a few weeks.

Authorities this week arrested a Florida man they say made comments about wanting to kill Biden. The man’s comments, both online and in person at a mental health facility, were made before Saturday’s assassination attempt of Trump, according to court papers.

Federal law provides Secret Service protection to former presidents and their spouses for life. The security posture around ex-presidents varies depending on threat levels and exposure, generally being toughest in the immediate aftermath of their leaving office and getting lower-profile — but never going away — as the years go on.

Trump is the first modern ex-president to seek another term, and because of his high visibility, his protective detail has always been larger than some of his peers. That protective bubble had only grown tighter in recent months as he became the presumptive Republican presidential nominee. All major party nominees are granted enhanced security details with counterassault and countersniper teams similar to the president.

Kennedy’s uncle, President John F. Kennedy, and his father, Sen. Robert F. Kennedy, were both assassinated.

Stepped up security impacts can didates as they campaign.

For Trump, a stricter security protocol could hamper his interactions. He often signs autographs, shakes hands and poses for selfies on airplane tarmacs and at events.

In many cities he visits, the campaign assembles supporters in public spaces like restaurants and fast-food joints. The images and video of his reception and interactions – circulated online by his campaign staffers and conservative media – have been fundamental to his 2024 campaign.