Anti-terror experts and officials fear ISIS and other terrorist groups could use off-the-shelf drones to drop bombs, and it's already happening in Syria and Iraq. These drones are the same ones commercially available everywhere, like this one used by Townsquare Media for aerial views at events.

The British newspaper The Sun reported this week a NATO chemical weapons expert and others warn these drones could be outfitted with World War I era mustard gas, which sears the lungs and proves lethal.

One of the branches of ISIS, called the Daesh militants, have already used drones to drop crude bombs in terror attacks in Syria.

British officials say without better registration and control of the drones, it would be all too easy to do the same there, or the U.S. In the Middle East, getting a drone off-the-shelf is easy, it's almost like buying a pack of batteries. No registration or information required.

One bomb attack in Syria last week that killed nearly 50 people was attributed to a drone dropping an improvised explosive device that detonated shortly after being delivered by a drone.