A U.S. expert who recently visited North Korea says Pyongyang seems optimistic about the resolution of the nuclear issue and ready to act for a nuclear-free Korean Peninsula.

David Albright, president and founder of the Institute for Science and International Security (ISIS), made the remarks Wednesday after a five-day visit to the communist country.

Albright met with North Korean Vice Foreign Minister Kim Kye-kwan and other officials during the trip.

Albright said that North Korean officials asked for large-scale energy aid, normalized ties with the U.S. and the unfreezing of North Korean accounts at Macao's Banco Delta Asia in return for freezing its nuclear reactor at Yongbyon and allowing U.N. inspections of its nuclear facilities.

Albright quoted Pyongyang officials as saying that nothing will happen until the U.S. agrees to build light-water reactors for the North as promised in the 1994 Geneva Agreed Framework.

The officials reportedly stressed that the scope of energy aid should be larger than the 500-thousand tons of heavy oil promised by Washington under the 1994 agreement.