TOKYO (AP) — The United States and Japan opened the door Sunday to new nuclear talks with North Korea if the saber-rattling country lowered tensions and honored past agreements, even as it rejected South Korea’s latest offer of dialogue as a “crafty trick.”

U.S. Secretary of State John Kerry told reporters in Tokyo that North Korea would find “ready partners” in the United States if it began abandoning its nuclear program.

Japan’s foreign minister, Fumio Kishida, also demanded a resolution to a dispute concerning Japanese citizens abducted decades ago by North Korean officials.

The diplomats seemed to point the way for a possible revival of the six-nation talks that have been suspended for four years.

China long pushed has for the process to resume without conditions. But the U.S. and allies South Korea and Japan fear rewarding North Korea for its belligerence and endless repetition of a cycle of tensions and failed talks that have prolonged the crisis.

Kerry’s message of openness to diplomacy was clear, however unlikely the chances appeared that North Korean leader Kim Jong Un’s government would meet the American’s conditions.

“I’m not going to be so stuck in the mud that an opportunity to actually get something done is flagrantly wasted because of a kind of predetermined stubbornness,” he told U.S.-based journalists.

“You have to keep your mind open. But fundamentally, the concept is they’re going to have to show some kind of good faith here so we’re not going to around and around in the same-old, same-old,” he said.

Tensions have run high on the Korean Peninsula for months, with North Korea testing a nuclear device and its intercontinental ballistic missile technology.

The reclusive communist state hasn’t stopped there. It has issued almost daily threats that have included possible nuclear strikes against the United States. Analysts and foreign officials say that is still beyond the North Koreans’ capability.

While many threats have been dismissed as bluster, U.S. and South Korean say they believe the North in the coming days may test a mid-range missile designed to reach as far as Guam, the U.S. territory in the Pacific where the Pentagon is deploying a land-based missile-defense system.

Japan is the last stop on a 10-day trip overseas for Kerry, who visited Seoul and Beijing as well in recent days.

In South Korea, he strongly warned North Korea not to launch a missile and he reaffirmed U.S. defense of its allies in the region. In China, he secured a public pledge from Beijing, the lone government with significant influence over North Korea, to rid the North of nuclear weapons.

Before returning to the United States, Kerry planned a speech Monday in Japan on the Obama administration’s Asia policy.

So far, Republican lawmakers in the U.S. have largely backed the administration’s efforts on North Korea.

U.S. Sen. Marco Rubio, R-Fla., told CBS’ “Face the Nation” that he was encouraged by Kerry’s China visit and that he hoped “we can get the Chinese to care more about this issue.

U.S. Sen. John McCain of Arizona suggested on CNN’s “State of the Union” that the U.S. make a counter-threat by using missile interceptors to hit any North Korean missile that is test-fired.

At each stop along his trip, Kerry stressed that the United States wanted a peaceful resolution of the North Korea situation six decades after a cease-fire ended the Korean War.

But North Korea on Sunday served a reminder of the difficult task ahead. Its Committee for the Peaceful Reunification of Korea said the government had no intention of talking with Seoul unless the South abandons its confrontational posture, as the North called it.

Seoul had pressed North Korea to discuss restarting operations at a joint factory park on the border and President Park Geun-hye has stressed peace opportunities after taking power from her more hard-line predecessor, Lee Myung-bak. The presidency expressed regret with North Korea’s rebuttal Sunday.

At a news conference in Tokyo, Kerry stressed that gaining China’s commitment to a denuclearized North Korea was no small matter given its historically strong military and economic ties to North Korea.

But he refused to say what the Chinese were offering to do concretely to pressure the North into abiding by some of the conditions it agreed to in a 2005 deal that required it to abandon its nuclear program.

“They have to take some actions,” Kerry said of North Korea. “How many or how much? I’d have to talk to folks back in Washington about that. But if the Chinese came to us and said, ‘Look, here’s what we have cooking,’ I’m not going to tell you I’m shutting the door today to something that’s logical and might have a chance of success.”

In remarks to U.S. journalists, Kerry said that under the right circumstances, he even would consider making a grand overture to North Korea’s leader, such as an offer of direct talks with the U.S.

“We’re prepared to reach out,” he said. Diplomacy, he added, required risk-taking and secrecy such as when President Richard Nixon engaged China in the 1970s or U.S. back-channel talks were able to end the Cuban missile crisis a decade earlier.

Given their proximity and decades of hostility and distrust, Japan and South Korea have the most to fear from the North’s unpredictable actions.

Kerry clarified a statement he made Saturday in Beijing, when he told reporters the U.S. could scale back its missile-defense posture in the region if North Korea goes nuclear-free.

It appeared to be a sweetener to coax tougher action from a Chinese government which has eyed the increased U.S. military presence in its backyard warily, but which has done little over the years to snuff out funding and support for North Korea’s weapons of mass destruction program.

Kerry said America’s basic force posture wasn’t up to debate. “There is no discussion that I know of to change that,” he said.

But he said it was logical that additional missile-defense elements, deployed specifically in response to the Korean threat, could be reversed if that threat no longer existed.

“I was simply making an observation about the rationale for that particular deployment, which is to protect the United States’ interests that are directly threatened by North Korea,” he said.

BRADLEY KLAPPER,Associated Press