Every state would have different rules regarding operation of UAVs. They may not even be contained in aviation legislation. A UAV may not even be considered an aircraft. But it would certainly be an 'activity' covered by some sort of law. ICAO int. rules really only apply to signatories, so if your UAV isn't a registered aircraft, it may not come under those rules. Invariably, there is some other law to cover activities hazardous to other aircraft (such as laser firing etc), but whether they would be enforcable 12nm offshore is open to debate.