Drone surveillance in the United States does not require a warrant, but the practice remains limited, the FBI told Sen. Rand Paul, R-Ky., in a letter after he placed a hold on James Comey’s nomination to be the new FBI director.

“[T]he FBI does not, and has no plans to use [unmanned aerial vehicles] to conduct general surveillance not related to a specific investigation or assessment,” Stephan Kelly, the assistant director at the FBI’s Office of Congressional Affairs, wrote Paul.