US authorities obtained intelligence from a human source in recent weeks on a plot by Iran to try to assassinate Donald Trump, a development that led to the Secret Service increasing security around the former president in recent weeks, multiple people briefed on the matter told CNN.

There’s no indication that Thomas Matthew Crooks, the would-be assassin who attempted to kill the former president on Saturday, was connected to the plot, the sources said.

The existence of the intelligence threat from a hostile foreign intelligence agency — and the enhanced security for Trump — raises new questions about the security lapses at the Saturday rally in Butler, Pennsylvania, and how a 20-year-old man managed to access a nearby rooftop to fire shots that injured the former president.