A system operative to down a target drone having propellers deployed along a perimeter (p), the system comprising: a processor-controlled interceptor drone bearing at least one processor-controlled flexible elongate intercepting agent cannon and at least one onboard camera; and an onboard processor operative to receive sensed wind conditions and to determine a firing distance ( d) between the interceptor and target drones, given a firing angle, wherein the firing distance ( d) is: predetermined, given at least wind conditions, to be large enough to allow at least a first predetermined amount of flexible elongate intercepting agent rolls fired by the cannon to each unravel to at least a predetermined extent before the flexible elongate intercepting agent rolls reach the target; and/or predetermined, given at least wind conditions, to be small enough to result in less than a further predetermined amount of unraveled flexible elongate intercepting agents scattering distally in excess of said perimeter, and wherein the processor is configured to track the target drone using imagery generated by the onboard camera including at least once, when said wind conditions exist, guiding the interceptor drone to a firing position whose distance from the target drone is the firing distance ( d), and commanding the cannon to fire at firing angle, once said firing position is achieved, thereby to use the flexible elongate intercepting agent to down target drones wherein at least one predetermined value for firing distance ( d) is stored in memory and wherein the interceptor continuously evaluates target range. a processor-controlled interceptor drone bearing at least one processor-controlled flexible elongate intercepting agent cannon and at least one onboard camera; and an onboard processor operative to receive sensed wind conditions and to determine a firing distance ( d) between the interceptor and target drones, given a firing angle, wherein the firing distance ( d) is: predetermined, given at least wind conditions, to be large enough to allow at least a first predetermined amount of flexible elongate intercepting agent rolls fired by the cannon to each unravel to at least a predetermined extent before the flexible elongate intercepting agent rolls reach the target; and/or predetermined, given at least wind conditions, to be small enough to result in less than a further predetermined amount of unraveled flexible elongate intercepting agents scattering distally in excess of said perimeter, predetermined, given at least wind conditions, to be large enough to allow at least a first predetermined amount of flexible elongate intercepting agent rolls fired by the cannon to each unravel to at least a predetermined extent before the flexible elongate intercepting agent rolls reach the target; and/or predetermined, given at least wind conditions, to be small enough to result in less than a further predetermined amount of unraveled flexible elongate intercepting agents scattering distally in excess of said perimeter, and wherein the processor is configured to track the target drone using imagery generated by the onboard camera including at least once, when said wind conditions exist, guiding the interceptor drone to a firing position whose distance from the target drone is the firing distance ( d), and commanding the cannon to fire at firing angle, once said firing position is achieved, thereby to use the flexible elongate intercepting agent to down target drones wherein at least one predetermined value for firing distance ( d) is stored in memory and wherein the interceptor continuously evaluates target range.