44 This duty concerns first and foremost the wealthier nations. Their obligations stem from the human and supernatural brotherhood of man, and present a three-fold obligation: 1) mutual solidarity—the aid that the richer nations must give to developing nations; 2) social justice—the rectification of trade relations between strong and weak nations; 3) universal charity—the effort to build a more humane world community, where all can give and receive, and where the progress of some is not bought at the expense of others. The matter is urgent, for on it depends the future of world civilization.
Source: Populorum Progressio (Vatican.va)