Where maritime drones are most useful

What role do medium-altitude, long-endurance drones have in maritime affairs?

They are very useful for peacetime maritime security and lower-level missions, though a major opponent would likely target them in a high-intensity conflict.

Medium-altitude, long-endurance drones are valuable for maritime security and lower-level counterterrorism tasks. Their persistence suits surveillance in peacetime and other lower-level missions. A capable adversary would probably try to eliminate them early in a major war. Even then, forcing that adversary to reveal itself and spend weapons or effort on the drones may have operational value. Peacetime usefulness does not guarantee survival in high-intensity combat.