From the Law of Nations or Principles of the Law of Nature   AD1758  :

If every man is, by his very nature, obliged to assist in promoting the perfection of others, much more cogent are the reasons which forbid him to increase their imperfection and that of their condition. The same duties are incumbent on nations (Prelim. §§5, 6). No nation therefore ought to commit any actions tending to impair the perfection of other nations, and that of their condition, or to impede their progress,—in other words, to injure them. This general principle forbids nations to practise any evil manoeuvres tending to create disturbance in another state, to foment discord, to corrupt its citizens, to alienate its allies, to raise enemies against it, to tarnish its glory, and to deprive it of its natural advantages.

http://lonang.com/library/reference/vattel-law-of-nations/

Source: CIA mind control morphed into psychiatry?