>Another idea to "force" US hand is to make it their problem in other ways. Dig it up, and threaten to leave it / break it on a place where currents flow towards continental United States.

It's not wise for small nations to give big nations the bird like that when there are other options. GP's suggestion is much more tactful because nobody worth taking seriously is going to argue with the idea of selling property to the highest bidder whereas dumping stuff in the ocean is generally frowned upon by everyone.