The thing with commerce raiders of any sort is, they're small and the ocean is large. Hunt and destroy tactics mostly involve stumbling on the right target, and Q-ships involve luck and the hope that they'll attack YOUR commercial vessel and not your friends'
Of course in this case it's made worse by the simple fact that just because it looks like a pirate boat doesn't mean it's a pirate boat, so the best known mean of destroying commerce raiders, airpower, runs afoul of political complications. Airpower is great when you can shoot on sight. (The other great Anti-Commerce-Raiders weapon, smashing their homeports, run into the same sort of complications, except worse)
I suppose if things keep getting worse and reach a point where something must be done, convoy tactics of some form may be looked into, although those are enormously resource-intensive.
Alternatively I suppose some sort of "You step in this part of the ocean without properly identifying yourself, we sink you" policy coupled with the use of airpower (I'm envisioning something perhaps more in the nature of one or two of those USMC amphibious assault ship coupled with two or three lightweight carriers from the Rest of the World) could be considered.
In either case, I don't think thesituation right now is bad enough to make either of those answer politically workable or cost-effective.
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