No report or listing, either official or otherwise, of "missing" or "missing in action" regarding any person in connection with any activity pertaining to or connected with the prosecution of any war in which the United States is then engaged, as such words "missing" or "missing in action" are used in military parlance, shall constitute or be interpreted as constituting actual knowledge or actual notice of the death of such principal or notice of any facts indicating the death of such person or shall operate to revoke the agency.