nuclear weapons remains as deep as ever. >> america preserves to resolve our concerns over iranian's nuclear programs peacefully, although, we are determined to prevent iran from developing a nuclear weapon. >> reporter: after decades of mistrust and estrangement from the00 crisis in 1979 to today's standoff over nuclear weapons, president obama said america and iran had start over. >> i don't believe this difficult history can be overcome overnight. the suspicions run too deep. but i do believe that if we can resolve the issue of iran's nuclear program, that can serve as a major step down a long road towards a different relationship. >> reporter: hours later, iran's president hassan rouhani sounded conciliatory in his first address to the world body saying he listened carefully to president obama's speech and hoped differences could be managed.