TOKYO – North Korea has vowed not to test missiles or nuclear weapons during proposed talks with the United States and South Korea, officials from South Korea said Tuesday after returning from surprisingly productive meetings in Pyongyang.

North Korea said it was prepared to hold “candid talks” with the United States about denuclearization and normalizing relations and “made it clear” that it would not resume provocations while engaged in dialogue, the officials said upon returning to Seoul.

North Korea did not confirm South Korea’s version of events, saying simply that the two sides “made a satisfactory agreement” during the meeting between the North’s leader, Kim Jong Un, and envoys sent by the South’s president, Moon Jae-in.

There is plenty of cause for skepticism. North Korea has previously said it will give up its nuclear weapons only if the United States withdraws its military from South Korea, and North Korea has previously reneged on every deal it has ever signed.

But the sudden thaw could also pave the way for talks between Kim’s regime and the Trump administration and bring about a reprieve in the months of acute tensions on the Korean Peninsula.

President Donald Trump said Tuesday there was “possible progress being made in talks with North Korea.”

“For the first time in many years, a serious effort is being made by all parties concerned,” he tweeted. “May be false hope, but the U.S. is ready to go hard in either direction!” he said, apparently suggesting he was open to both diplomacy and military action for dealing with North Korea.

These developments, however, come at a time when the United States has no ambassador in South Korea and no special representative on North Korea, and when the nominee for assistant secretary of state for East Asia has yet to be confirmed by the Senate.

During its visit to Pyongyang, a delegation led by Chung Eui-yong, the South Korean national security adviser, had a four-hour dinner with Kim and his wife, as well as other senior officials including Kim’s sister, Kim Yo Jong, who went to South Korea for the opening of the Winter Olympics last month.

“The dinner proceeded in a warm atmosphere overflowing with compatriotic feelings,” the North’s official Korean Central News Agency said in a report, one of several that mentioned the Koreans’ shared blood and implied that they were united together against the outside world.

Chung, who will travel to Washington later this week to brief Trump administration officials, returned to Seoul with an agreement that surprised analysts with its scope.

Vice President Mike Pence – who attended the Olympics opening ceremony – said the United States and allies seek to keep “maximum pressure” on the North if talks emerge or not.

“All options are on the table and our posture toward the regime will not change until we see credible, verifiable, and concrete steps toward denuclearization,” said a statement from Pence.

In Korea during the Olympics, Pence met with the South’s president, Moon. But a planned encounter with Kim’s sister was scrapped by North Korea.

North Korea “made it clear” that it would not resume provocations – such as nuclear tests or intercontinental ballistic missile launches – while it was engaged in talks with the South, he said. This commitment comes even as the U.S. and South Korean militaries prepare to start huge annual drills that North Korea considers preparation for an invasion and that typically lead to a sudden increase in tensions on the peninsula.

The regime reiterated a willingness to talk with the United States, its avowed enemy since the Korean War, and “clearly affirmed its commitment to the denuclearization of the Korean Peninsula,” Chung said once back in Seoul.

If events play out the way Seoul hopes, Moon will be meeting Kim for a summit on the southern side of the inter-Korean border late next month.

Moon’s progressive predecessors both traveled to Pyongyang for summits with Kim’s father, Kim Jong Il. Analysts had said it would be unseemly for a South Korean leader to make the same pilgrimage a third time.

The two sides agreed that the next summit will be held inside Peace House at Panmunjom, the “truce village” straddling the Demilitarized Zone that divides the peninsula. The house is just over the southern side of the border line.

This would be the first time since the Korean War ended in 1953 that the North Korean leader had crossed into the South and the first meeting between Kim and another head of state in his six years in power.

The two Koreas also agreed to establish a hotline between the leaders of the two sides to ease military tensions and to be able to consult closely. They will test the line with a phone call before the summit.

“This is a potentially significant development, but it’s too soon to judge,” said Scott Snyder, a Korea expert at the Council on Foreign Relations. The Trump administration would want to hear the same message directly from the North Koreans, he said.

North Korea has a history of striking bargains with the outside world, almost always involving some kind of payment for some kind of weapons freeze. But it has quickly broken the deals that it has signed, including the 1994 “agreed framework” and a 2005 denuclearization deal struck during now-defunct six-party talks.

This track record suggests that skepticism about this tentative agreement is warranted.

“I’d caution against too much optimism because we’ve been down this road too many times before,” said Abraham Denmark, a former Asia official at the Pentagon, now director of the Asia program at the Wilson Center.

“Even if it’s eventually successful, it’s going to be difficult. There will be setbacks and uncertainty,” Denmark said.

But the development also offers a welcome glimmer of hope after months of talk emanating from Washington about military options for dealing with North Korea’s nuclear advances.

Almost every Korea expert in Washington agrees that there are no good military options for dealing with North Korea.

With this diplomatic gambit, Moon is managing to stave off talk of strikes at least for now, said Gordon Flake, a longtime Korea expert in Washington who is now at the University of Western Australia.

“Moon sees the same things in D.C. that the rest of us see,” Flake said. “He’s trying to buy some time to figure out some kind of peace.”

The Washington Post’s Brian Murphy and Philip Rucker in Washington contributed to this report.

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