When pollution prevention fails, preparedness and response is of paramount importance. Coastal states will organize this in their own interest in their adjacent waters, and states often sign cooperation agreements with other states applicable there. However, who is responsible for the high seas, and is there a right to intervene there? Is there a difference in this respect between the high seas and the eezs? The chapter discuses different bases for intervention, including the intervention conventions, the salvage conventions and the doctrine of necessity, and, in addition, whether a basis for intervention at all is necessary. The financial position of a state requesting assistance is discussed in relation to assisting states and the polluter.