Did you read the article? They aren't arming the dolphins.

The dolphins are scouts for intruding mines and infiltrators - they find something strange, they come back and report it, and are sent out with a buoy to mark it, or attach to the intruder to float them for capture.

Someone could make a compelling argument that US' global military dominance imposes a kind of Pax Americana that is net beneficial to the human condition, and this is one limb of that military dominance.