The Navy League’s on line magazine, Seapower, reports,

 To improve capabilities for monitoring aircraft and vessels carrying illicit maritime cargo such as drugs, for longer periods of time and over greater distances, the Office of Naval Research-sponsored SCOUT initiative recently conducted a dynamic experimentation event at Joint Expeditionary Base Little Creek-Fort Story, Virginia, at the entrance of the Chesapeake Bay.
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The goal of the event was to find creative solutions to pinpoint “dark targets” — aircraft or watercraft operating with little to no radio-frequency signatures — found in maritime operating areas covered by the Joint Interagency Task Force South, ONR said in a Sept. 19 release. It sought ways to use unmanned technologies to expand intelligence, surveillance and reconnaissance capabilities beyond those of traditional maritime patrol aircraft such as the P-3 Orion and P-8 Poseidon.

Notably this includes aircraft as well as surface craft.

Thanks to Lee for bringing this to my attention.