The Federal Aviation Administration says there are now more registered drone operators in the United States than there are registered manned aircraft.

FAA Administrator Michael Huerta told a legal forum on Monday that the agency passed the milestone last week when it topped 325,000 registered drone owners. There are 320,000 registered manned aircraft.

Huerta said the number of small unmanned aircraft is even larger because drone operators often own more than one drone.

FAA officials launched a drone-registration program just before Christmas, saying it would help them track down operators who violate regulations and also help create a culture of accountability.

Huerta said the speed with which registration has taken off is proof that government and industry can work together.

Under the new regulations, drone operators are required to register their unmanned aircraft and apply their registration number to the drone. The same number could be applied to other drones they own as well.

Registration costs $5 for three years, but the fee was waived for the first 30 days since the registration opened in the third week of December.

Applicants are required to provide a name, address and email address. In addition to affixing the registration number to the drone, people are required to carry their FAA registration when operating the aircraft.

If a drone is sold by its initial owner or given as a gift, the new owner must register it.

Drones weighing between half a pound and 55 pounds must be registered. Drones above that weight go through normal FAA registration requirements for aircraft.

Failure to register or improper use of a drone could carry a civil penalty of up to $27,500, and a criminal conviction could cost as much as $250,000 and three years in prison.

Washington Post staff writer Ashley Halsey contributed to this report.