Figures that it *wasn’t* a Harpoon. Sending a $1m Harpoon at a tugboat costing a few hundred grand isn’t the most cost-effective way of targeting it, especially given that these (typically) non-naval vessels don’t exactly have much in the way of defenses.
A “few hundred grand”? This isn’t Little Toot on the Thames - the cost of an ocean-going tug starts at several million.