North Korean demands for large amounts of energy aid are frustrating negotiations aimed at dismantling North Korea's nuclear programs, Japan's envoy to the talks said Sunday. "North Korea has excessive expectations on energy aid," Kenichiro Sasae of the Japanese Foreign Ministry told reporters on his way to a fourth day of the six-nation talks. "This is the problem, and unless they change their thinking an agreement will be difficult." Since the talks second day, envoys have said that negotiations were getting bogged down on a single issue. Sasae's comments were the first time any of the envoys - from the United States, China, Russia and South Korea as well as Japan and North Korea - had publicly specified the sticking point.