WASHINGTON – It remains unclear if the next round of six party talks – promised before the end of September but now not expected before early October at best – will take place at all. If it does, it will likely represent the last chance before the U.S. elections to test whether diplomacy can roll back North Korea’s nuclear programs. Few expect them to succeed. Meanwhile, North Korea is moving steadily toward a full-fledged nuclear arsenal, including long-range ballistic missiles.