[ElectricStrawberry]

Drop some nukes on the damned things. At sea, the ecological damage and fall-out is non-existant.
End of story

[Mr. Mojo]

Exactly. We used to blow up whole islands every other week in the So. Pacific in the 50's ....with serious multi-megaton H-bombs. Dropping a small tactical nuke on each of these ships would be environmentally benign by comparison.