Tokyo ? As Secretary of State Colin Powell arrived in Japan hoping to restart talks aimed at ending North Korea’s nuclear program, North Korea threatened Saturday to double its nuclear capabilities unless Washington ends its “hostile policy” toward the reclusive communist nation.

In addition to demanding an end to U.S. hostility, North Korea is insisting that it promise immediate aid and agree to discuss South Korea’s past nuclear experiments before talks on North Korea’s nuclear program resume.

Powell, at the start of a quick trip to Japan, China and South Korea, said that Pyongyang should discuss its concerns about U.S. hostility in new negotiations over ending its nuclear weapons programs, rather than demanding the United States meet new conditions before talks can start.

North Korea can bring up anything in the negotiations, Powell told reporters traveling with him. “But to put forward these kinds of conditions that may lead to yet another set of conditions is not the way to solve this problem,” Powell said.

In the latest salvo, North Korea’s official newspaper, Rondong, warned in a commentary Saturday that “If the United States persistently pursues its confrontational hostile policy towards the DPRK (Democratic People’s Republic of Korea), it will only compel the DPRK to double its deterrent force.”

North Korea often uses the term “deterrent force” to describe its nuclear program.

Powell told reporters during his flight to Tokyo that the United States and the four other countries involved in the talks with North Korea — Japan, China, Russia and South Korea — were “constantly” looking for ways to make adjustments in their positions that would help get the problem of North Korea’s nuclear program solved faster. Overall, he said, all four countries support a proposal the United States put forward in the third and last round of North Korea talks in June.

Under that plan, once North Korea declared it planned to give up its nuclear weapons programs, South Korea and Japan would start to provide it with fuel for energy. North Korea also wants the United States to provide a formal security agreement guaranteeing it would not attack. Powell said that guarantee could be given after North Korea gives “some expression of seriousness” about ending its nuclear weapons programs.

The United States reached an agreement with North Korea in 1994 to halt its nuclear programs in exchange for aid. In 2002, however, North Korea acknowledged it had reneged on the pledge and had started a secret program to build nuclear weapons.