The FBI uses drones for domestic surveillance purposes, the head of the agency told Congress early Wednesday.

Robert Mueller, the director of the Federal Bureau of Investigation, confirmed to lawmakers that the FBI owns several unmanned aerial vehicles, but has not adopted any strict policies or guidelines yet to govern the use of the controversial aircraft.

“Does the FBI use drones for surveillance on US soil?” Sen. Chuck Grassley (R-Iowa) asked Mr Mueller during an oversight hearing on Capitol Hill Wednesday before the Senate Judiciary Committee.

“Yes,” Mueller responded bluntly, adding that the FBI’s operation of drones is “very seldom.”

Asked by Sen. Dianne Feinstein (D-California) to elaborate, Mueller added, “It’s very seldom used and generally used in a particular incident where you need the capability.” Earlier in the morning, however, Mueller said that the agency was only now working to establish set rules for the drone program.

Mueller began answering questions just after 10 a.m. EDT. He briefly touched on the recently exposed NSA surveillance program that has marred the reputation of the United States intelligence community. Mueller said 22 agents have access to a vast surveillance database, including 20 analysts and two overseers.

When Sen. Al Franken (D-Minnesota) asked Mueller later in the morning if he’d consider being more open about the FBI’s surveillance methods, the director expressed reluctance to be more transparent. Mueller said the FBI has and will continue to weigh the possibility of publishing more information about its spy habits, but warned that doing so would be to the advantage of America’s enemies.

“There is a price to be paid for that transparency,” Mueller said. “I certainly think it would be educating our adversaries as to what our capabilities are.” 

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