The small consumer drones that now number in the millions in the U.S. pose a growing threat as terrorist and criminals fine tune their use and a Senate leader says he’ll push legislation to let U.S. authorities bring suspect craft down.

The devices have already been used to smuggle contraband into prisons and to conduct surveillance of sensitive sites, and homeland security and law enforcement agencies fear that it’s only a matter of time before they’re used to conduct attacks, a Senate hearing Wednesday was told.

“This isn’t a theoretical threat,” said Senator Ron Johnson, the Wisconsin Republican who is chairman of the Homeland Security and Government Affairs Committee. “I was shocked that we don’t have the authority to counter this.”

Johnson and the committee’s ranking Democrat, Senator Claire McCaskill of Missouri, have sponsored legislation that give . s the Department of Homeland Security and the Department of Justice power to monitor drone communications and to bring them down if warranted.

Johnson hopes to attach the drone legislation to a bill authorizing the Defense Department. The bill is expected to be taken up by the Senate within weeks, Johnson said.

Currently, those agencies are prohibited from many of those actions because of existing laws prohibiting wireless surveillance and interfering with radio broadcasts. The Defense Department is the only agency with limited authority to bring down drones at secure facilities.

Front-line officers are at risk of violating the law “just for doing their jobs,” said Hayley Chang, DHS’s deputy general counsel.

The White House has been urging lawmakers for the past year to update the law on counter-drone activities.