The cardinal was giving the keynote address at a two-day conference commemorating the 50th anniversary of Pope John XXIII's encyclical on peace-building, Pacem in Terris, that was attended by some 300 Catholic academics and US policymakers.
The conference was hosted by Catholic University of America's Institute for Policy research and Catholic Studies.
Cardinal Turkson said the goal of peace continues to be frustrated because "the building-block of nation has persistently been a stumbling-block".
He continued: "Even when ... nations resolve to seek peace via an arrangement like the League of Nations or the United Nations, the starting point of nation scuttles the enterprise: ultimately, a nation will pursue its interests above those of any set of nations."