; (25) the term environmental emergency means any event that occurs after the entry into force of Annex VI, and that results in, or imminently threatens to result in, any significant and harmful impact on the Antarctic environment; (26) the term nongovernmental operator means any operator other than a governmental operator or a contractor or subcontractor acting on behalf of any governmental operator; (27) the term operator means any person who organizes activities (including tourist activities) in the United States to be carried out in Antarctica, and any person who organizes activities (including tourist activities) in a country other than the United States to be carried out in Antarctica if such person has its principal place of business or habitual place of residence in the United States, or is incorporated in the United States, except that the term operator does not include— (A) an individual who is an employee, contractor, subcontractor, or agent of, or who is in the service of, a person who organizes activities to be carried out in Antarctica; (B) a contractor or subcontractor acting on behalf of any governmental operator; or (C) any person who organizes only fishing activities to be carried out in Antarctica; (28) the term reasonable , as applied to preventative measures and response action , means measures or actions which are appropriate, practicable, proportionate and based on the availability of objective criteria and information, including— (A) risks to the Antarctic environment, and the rate of its natural recovery; (B) risks to human life and safety; and (C) technological and economic feasibility