Refugee children listen to music Saturday as part of therapy at a French-run center for Rwandan children with psychological disorders in Goma, Zaire. Psychologists at the center say that many children suffer mental disorders as a result of witnessing the horrors of Rwanda's civil war. Meanwhile, in Kigali, Rwanda's capital, U.S. National Security adviser Anthony Lake said the United States will do everything it can to prevent a repeat of the Rwanda massacres that swept the tiny country while the world watched. Lake is the most senior U.S. official to visit Rwanda since the massacre of what is believed to be a million people between April and July of this year. He said the first step would be to boost the country economically. "The United States will do everything it can to prevent that (genocide) ever happening again in Rwanda," he told reporters after visiting a mass grave.