North Korea says main nuclear complex operational; warns U.S.

By Jack Kim and Ju-min Park SEOUL (Reuters) - North Korea said on Tuesday its main nuclear complex was operating and it was working to improve the "quality and quantity" of weapons which it could use against the United States at "any time." The comments on North Korea's official news agency came after its space agency said late Monday it was readying a new satellite for launch, indicating it may fire an upgraded long-range ballistic missile timed around the 70th anniversary of its ruling party o