US Secretary of State John Kerry headed to Seoul on Thursday for discussions on North Korea's nuclear programme, a day after high-level inter-Korean talks failed to resolve a row over looming South Korea-US military drills.
South Korea is Kerry's first stop on an Asia tour that will also take him to Beijing and Jakarta with a focus on regional tensions stoked by China's territorial claims.
As well as discussing efforts to rein in Pyongyang's nuclear weapons programme, Kerry will be briefed in Seoul on a diplomatic initiative that saw the two Koreas sit down Wednesday for their highest-level official talks since 2007.
The discussions ran late into the night, and ended without any tangible agreement or joint statement, although Seoul said both sides had committed to keep the dialogue going.
Although there had been no fixed agenda, the South had focused on ensuring that a planned reunion later this month for family members separated by the 1950-53 Korean War goes ahead as scheduled.
The February 20-25 event overlaps with the start of South Korea's annual joint military exercises with the United States, which Pyongyang condemns as provocative and insists should be called off.
A South Korea statement issued after the talks said the North side had demanded that the joint drills be postponed until after the reunion was over.
Seoul declined on the grounds that there should be no link between what are purely separate humanitarian and military issues.
There was no immediate comment from North Korea.
Briefing reporters in Seoul, presidential spokesman Min Kyung-wook indicated that the talks had been a good opportunity for the two rivals to sound each other out.
"We've become clearly aware of North Korea's intentions, and this was also an opportunity for us to clearly explain our principles," he quoted a government official as saying.
- Kerry to seek China pressure on North Korea -
It was not clear if there was any discussion of North Korea's nuclear programme, which will be the main focus of Kerry's visit.
North Korea and its main ally China have called for a resumption of six-party talks on the North's nuclear ambitions, but Washington and Seoul both insist that Pyongyang must first demonstrate some tangible commitment to abandoning nuclear weapons.
In Beijing, Kerry is expected to push China to exert more pressure on its ally to prove it is serious about wanting to restart the six-party process.
"The days are long gone when the international community will take North Korea's IOU ... words alone will not do," a State Department official told reporters flying with Kerry.
Washington's current unwillingness to offer incentives such as food aid to lure Pyongyang back to the negotiation table "is a pressure point that we hope will lead North Korea to make the right choice," the State Department official said.
North Korea had the opportunity to end its international isolation, but had to take "convincing steps," he said, adding that Washington wanted to turn "denuclearisation from a noun into a verb".
The US has also repeatedly called for the isolated North to release Kenneth Bae, a Korean-American missionary who was sentenced to 15 years' hard labour last year on sedition charges.
The State Department on Tuesday again voiced frustration that an invitation to US envoy Robert King to discuss Bae's case was extended on February 5 but withdrawn just three days later.
US officials called on North Korea to show "compassion" for the 45-year-old, who is forced to work 10 to 12 hours a day even though his health is failing.
During his brief stay in Seoul, Kerry will meet with President Park Geun-Hye, who came to office a year ago on a campaign promise of greater engagement with Pyongyang.
Wednesday's talks, which were held at Pyongyang's instigation, had raised hopes that the two sides might be ready to embark on a genuine trust-building dialogue.
But South Korea remains wary of the impoverished North's intentions, suggesting that Pyongyang's only real desire is to see the resumption of several lucrative cross-border projects.
Paik Hak-Soon, an analyst at the Sejong Institute in Seoul, stressed there was still room for optimism.
"At least these senior officials met for the first time in a very long time," Paik.
"You can't expect them to produce a major decision at the first meeting. They go back to the capitals, talk with their leaders and will likely meet again after the South-US army drill is over," he added.