Seoul, Washington and Beijing are intensifying diplomatic efforts as they wrestle to rein in North Korea’s nuclear threats and find middle ground in reopening a long-stalled six-nation forum aimed at disarming the communist country.

Hwang Joon-kook, Seoul’s new special representative for Korean peninsular peace and security affairs and top envoy to the six-party talks, returned home after separate trips to Washington and Beijing over the last week.

In Washington, Hwang and his U.S. and Japanese counterparts sent a strong warning to Pyongyang against a fourth nuclear test and vowed to step up cooperation to preclude any further provocations.

But controversy is brewing after a ranking Seoul official displayed willingness to apply “flexibility” toward the preconditions for what would be the first gathering in more than five years.

“The position of the five countries (excluding North Korea) remains essentially unchanged that we cannot accept North Korea as a nuclear state, and it’s imperative for them to show sincerity toward denuclearization,” the official told reporters in the U.S. capital.

“But in terms of presteps, we can think about the definition of the word ‘pre’ with flexibility.”

His remarks imply a softened stance for South Korea and the U.S. compared with their previous demand for preemptive, stronger commitments from the North than those enshrined in the now-defunct Feb. 29, 2012, agreement.

In the so-called “leap day deal,” Pyongyang agreed to put a moratorium on its nuclear program, cease atomic and missile tests and let in international inspectors in return for 240,000 tons of food aid from Washington.

At her recent three-way summit with the leaders of the U.S. and Japan, President Park Geun-hye also indicated progress in her position, saying the allies can “explore various ways to resume dialogue if there is a guarantee that we can make substantive progress on the denuclearization front and block North Korea from beefing up its nuclear capabilities.”

In Beijing, Hwang and Wu Dawei, China’s top nuclear envoy and special representative for Korean affairs, discussed ways to resume “meaningful dialogue” while boosting consultations to deter Pyongyang from an additional underground explosion.

Wu, for his part, is scheduled for rounds of talks with U.S. Special Representative for North Korea Policy Glyn Davies from Monday through Thursday in New York and Washington. Wu also traveled to Pyongyang last month, while Choi Son-hui, director general of the North Korean Foreign Ministry, was in Beijing the following week.

The series of back-to-back visits reflect the countries’ efforts to revive momentum for the six-way gathering also involving Russia, which had picked up until the execution of North Korean leader Kim Jong-un’s once powerful uncle, Jang Song-thaek, in December.

But other Seoul and Washington officials cautioned against overinterpreting the “flexibility” remarks, saying no concrete ideas were being floated for the restart of the talks and tension remains high on the peninsula on the back of Pyongyang’s threats of a nuclear test and military drills on both sides of the border. Some dismissed the comment as a “slip of the tongue” driven by extensive attention.

“In terms of the North Korea issue, our external messages can sometimes be clear and other times confusing,” a top South Korean diplomat told reporters on customary condition of anonymity.

“It’s more complicated than raising or lowering the threshold for talks. … During consultations, which may take two to three weeks at the minimum or more than a month in other cases, the five parties would able to reach common ground for the conditions to restart dialogue.”

Another senior official said: “The current situation is no more than that discussions are being revitalized on how to reopen the six-party talks after a letup brought about by Jang’s execution.”

U.S. State Department spokesperson Jen Psaki also said that nothing has changed regarding their approach.

“Obviously, there are steps North Korea would need to take. The ball remains in their court,” she told reporters on Friday.

By Shin Hyon-hee (heeshin@heraldcorp.com)