Drones in the USA

FBI Director Robert Mueller acknowledged the law enforcement agency uses drone aircraft in the United States for surveillance in certain difficult cases.

Mueller told the Senate Judiciary Committee on Wednesday that drones are used by the FBI in a "very, very minimal way and very seldom."

He did not say how many drones the FBI has or how often they have been used.

A federal law enforcement official said the aircraft have been used for surveillance in hostage situations and also when suspects have taken refuge behind barricades.

"We use it sparingly in dangerous situations where the risk to agents lives are at stake," the official told CNN.

Sen. Charles Grassley, an Iowa Republican, asked Mueller whether the FBI had guidelines for using drones that would consider the "privacy impact on American citizens."

Mueller replied the agency was in the initial stages of developing them.

"I will tell you that our footprint is very small," he said.

Senate Intelligence Committee Chairman Dianne Feinstein expressed concern over drone use domestically.

"I think the greatest threat to the privacy of Americans is the drone and the use of the drone, and the very few regulations that are on it today and the booming industry of commercial drones," the California Democrat said.

Mueller said he would need to check on the bureau's policy for retaining images from drones and report back to the panel.

"It is very narrowly focused on particularized cases and particularized needs and particularized cases," said Mueller. "And that is the principal privacy limitations we have."

Members of Congress and privacy advocates have pressed for regulations on the use of drones.

Targeting Americans with lethal force in counterterror operations overseas was a controversy that flared publicly during confirmation hearings for CIA Director John Brennan earlier this year.

Senators aggressively sought the administration's legal reasoning for those operations.

Some lawmakers were critical of the practice and questions were raised about whether drones might ever be used against U.S. citizens suspected of terrorism who were on American soil.

Sen. Rand Paul, a Kentucky Republican, staged a filibuster in March over the issue.

Attorney General Eric Holder told Paul in a letter that said in part, "the U.S. government has not carried out drone strikes in the United States and has no intention of doing so."