Mankind's preoccupation with survival in this age has given renewed impetus to the idea of a world community deeply concerned with the prevention of friction between nations. The achievement to date has been largely in terms of efforts to control acts of aggression committed by governments. Most people have assumed that the military rivalry between the great powers is the only threat confronting the world today. While readily conceding that this threat has placed mankind in a highly precarious situation, this book, on the other hand, reflects my conviction that any program designed to attain world peace will be significantly incomplete without the control of hostile actions which private persons have been known to commit against foreign nations. Experience shows that these actions not only endanger the good re­ lations between states, but are also likely to plunge the world com­ munity into wars, thus spreading destruction and human suffering everywhere.