The Defense Department hasn't officially said what it used against the drone, but MADIS was present aboard the Boxer at the time. You can see it on top of the tan vehicle in the photo above.

The incident illustrates the rapidly changing nature of warfare. Increasingly, the US is finding ways to take action against military targets without firing a shot -- it reportedly used a cyberattack to disable Iranian missile control systems in June. These theoretically avoid sparking fiercer conflicts. The question, as you might imagine, is whether or not this will avoid prompting escalations that could include conventional military responses. While Iran hasn't launched full-scale counterattacks of its own at this stage (its seizure of ships isn't a straightforward response), there are concerns that these 'softer' methods could still prompt fiercer reactions in certain circumstances.