Japan demanded Friday that North Korea reverse its decision to quit the global nuclear arms control treaty and address growing fears in the region about its suspected weapons program.

North Korea announced it had withdrawn from the Nuclear Non-Proliferation Treaty. It blamed what it said was U.S. aggression toward it, but said it would not develop nuclear weapons "at this stage."

"Our nation will strongly demand from North Korea a quick retraction of its statement and a positive response to solving the nuclear weapons problem," Japanese Chief Cabinet Secretary Yasuo Fukuda said in Tokyo.

Fukuda said Japan will work closely with the United States, South Korea and other nations as well as the U.N.'s International Atomic Energy Agency to address the crisis.

North Korea's announcement was the latest in a series of saber-rattling remarks from the isolated communist state. They have raised tensions in the region over Pyongyang's suspected nuclear weapons and missile development.

North Korea alarmed the world in December by taking steps to reactivate nuclear facilities frozen under a deal with Washington in 1994 and then expelling U.N. monitors.

Friday's comment was Pyongyang's first official reaction after the United States, South Korea and Japan offered dialogue to resolve the dispute in a joint statement.

But Washington has ruled out U.S. incentives for the North to stop its nuclear weapons program.

Shinichi Kitaoka, a North Korea expert and professor at the University of Tokyo, said North Korea was trying to win international food aid and shake the United States into a compromise when Washington is preoccupied with preparing for a possible war in Iraq.

While ruling out threat of imminent attack from North Korea, Kitaoka said the increasingly hard-line approach reflects the country's severe food shortage and desperate need for aid in the next couple of months.

"An immediate risk is small overall, but we can't be too optimistic. It's a crazy nation," Kitaoka said in a telephone interview.

Japanese in Tokyo said they were worried.

"I feel scared because we never know how that country is going to act," said Kayoko Kataoka, 54, who works at a tea store.