"Like, woooow man! Hellooo! Are you serious right now?" Daoud exclaimed at one point on the recording.

Near the end of the conversation, the agent told Daoud that his group was interested in doing "something in Chicago" because of fewer security risks than in New York.

Daoud expressed interest but also seemed to have little grasp or understanding of how such an attack could be orchestrated. At one point, Daoud brought up the idea of using "flying cars" to bomb a location, saying he was sure they existed and were "less expensive than a plane."

"You could get 20 of those. It would be much cheaper than getting, like, five airplanes," Daoud said.

The agent threw cold water on the idea, saying that it would be "a thing that would take years and years to plan" and cost a lot of money.

The conversation ended with the agent suggesting Daoud write his ideas on targets and methods down in a notepad and give them to him at their next meeting.

Asked why he suggested that to Daoud, the agent testified it was important that Daoud had time to "cool off" and potentially walk away from the idea of an attack. The FBI also wanted any specific plan for an attack to be Daoud's idea, the agent said.