Catechism of the Catholic Church §2438 — excerpt
Various causes of a religious, political, economic, and financial nature today give "the social question a worldwide dimension." There must be solidarity among nations which are already politically interdependent.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: SRS 9 · SRS 17 · 45 · CA 28 · 35