Which of the following is the most extreme form of Dispute Settlement ?

Intervention is dictatorial interference by one State in the affairs of another to impose its will, and it is regarded as the most extreme of the compulsive means of settling disputes short of war. Retorsion answers an unfriendly but lawful act with a similar lawful act, and reprisal answers an illegal act with a retaliatory act. A pacific blockade only stops access to or from the ports of the other State.