North Korea said Saturday it was willing to abandon its nuclear weapons programs, but it demanded a change in American policy as a California congressman critical of the communist state's human rights records visited Pyongyang. The statement, which echoed the North's earlier stance, appeared to be timed for a visit by Rep. Tom Lantos, the ranking Democrat on the House International Relations Committee.It also came a day after U.S. officials said one of Washington's harshest critics of North Korea, Undersecretary of State John Bolton, will resign his post. "Our consistent stance is to denuclearize the Korean peninsula and resolve the problem through dialogue," said a spokesman of North Korea's Foreign Ministry. "If the United States really wants to resolve the nuclear problem through dialogue, it should show through action that it is giving up a hostile policy aimed at toppling our system, and take the road toward coexistence."