120 Furthermore, relations between States must be regulated by the principle of freedom. This means that no country has the right to take any action that would constitute an unjust oppression of other countries, or an unwarranted interference in their affairs. On the contrary, all should help to develop in others an increasing awareness of their duties, an adventurous and enterprising spirit, and the resolution to take the initiative for their own advancement in every field of endeavor.
Source: Pacem in Terris (Vatican.va)