South Korea, the U.S. and China are ramping up diplomatic efforts amid growing signs of North Korea preparing for a long-range missile test.

Lim Sung-nam, the Foreign Ministry’s special representative for Korean Peninsula peace and security affairs, arrived in Beijing on Thursday to meet with his Chinese counterpart Wu Dawei and other officials for two days. Lim is chief negotiator to a six-party forum on denuclearizing the North and expected to swap views over the situation on the peninsula.

Deputy Foreign Minister Kim Kyou-hyun is in Washington for discussions with officials including Kurt Campbell, assistant secretary of state for East Asian and Pacific Affairs.

Vice Foreign Minister Ahn Ho-young also held a two-day strategic dialogue with his Chinese counterpart Zhang Zhijun in Beijing early this week.

The series of high-level meetings coincide with a four-day visit by Liu Qibao, head of the Chinese Communist Party’s Publicity Department, to North Korea, Laos and Vietnam. In Pyongyang, he is speculated to deliver Beijing’s messages urging it to refrain from any missile liftoff.

Seoul officials played down the significance of their trips saying they are part of regular exchanges between partners.

“They may appear to be carefully calibrated consultations on their common agenda but you could end up over-interpreting the whole situation,” a senior official at the Foreign Ministry told reporters on customary condition of anonymity.

“Now that the U.S. has completed its presidential election and China’s new leadership has begun, we should naturally exchange opinions with each other, especially with the missile issue emerging.”

DigitalGlobe Inc., a U.S.-based commercial satellite operator, has released new images taken on Nov. 23 showing increased activity at the North’s launch site in the western town of Dongchang.

The North “could possibly conduct its fifth satellite launch event during the next three weeks,” the company said Monday, saying that the type of work is consistent with preparations detected at the same place before its botched rocket liftoff in April.

Pyongyang insists on its right to the peaceful use of space technology by sending a satellite into orbit. But the international community has blasted it as a cloaked test for a ballistic missile and a violation of U.N. bans on any nuclear or missile activity by the communist state.

U.S. officials have reportedly informed their South Korean and Japanese counterparts that its satellite spotted North Koreans transferring missile components from a Pyongyang plant to the Dongchang facility.

Seoul’s Foreign Ministry and the U.S. Department of State declined to discuss intelligence issues.

Hong Lei, the Chinese Foreign Ministry’s spokesperson, said he has acknowledged the news reports.

“It’s the common responsibility and shared interest of all parties concerned to maintain the peace and stability of the Korean Peninsula,“ he told a Tuesday briefing.

Meanwhile, speculation is rising that senior U.S. officials made a covert four-day trip to Pyongyang starting on Aug. 17.

Donga Ilbo newspaper cited diplomatic sources as saying that a U.S. Air Force jet departed from Guam, possibly carrying Daniel Russel, the White House’s senior director for Asian affairs, and Sydney Seiler, chief of North Korea policy at the presidential office’s National Security Council.

The report followed earlier rumors that Seiler and Joseph DeTrani, a North Korea expert and director of the National Counterproliferation Center, had visited the North Korean capital a week before the April 13 launch in an apparent attempt to discourage the plan.

A White House spokesperson told Yonhap News in Washington that it has “no information to provide.“

Seoul’s Foreign Ministry “viewed the report but has no knowledge” related to the visit, spokesman Cho Tai-young told a briefing on Thursday.

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