Tension is escalating over North Korea's suspected preparation for a rocket launch, apparently aimed at raising the stakes in its relations with Seoul's next government and the Obama administration in its second term.
US satellite imagery has captured increased movement at the North's Sohae launch station in the western town of Dongchang.
Analysts say that the possibility is not so high for the North to proceed with the launch but the activity may upend burgeoning hopes for a thaw in cross-border relations.
A possible launch will constitute a breach of UN bans on any nuclear and missile activity by the heavily militarised country. Pyongyang, in contrast, claims to have been trying to put a civilian satellite into orbit.
The signs come about three weeks before South Koreans elect their president for the next five years. Both of the two leading candidates, Park Geun-hye of the ruling Saenuri Party and Moon Jae-in of the main opposition Democratic United Party, have vowed to engage Pyongyang and resume bilateral economic projects.
Fresh off reelection, US President Barack Obama also showed his willingness to talk if the reclusive regime drops its nuclear ambitions and "chooses the path of peace and progress" in his speech in Myanmar early this month.
"The situation warns that we could step off on the wrong foot and have difficulty dealing with the North for at least six months to all year next year," said Hong Hyun-ik, a senior researcher at Sejong Institute, a private think tank near Seoul.
"It's extremely difficult to forecast when they'll fire it. Under the current circumstances at large, they're unlikely to go ahead anytime soon but they may have as usual their own calculations and schedule."
US officials have reportedly informed their South Korean and Japanese counterparts that its satellite detected North Koreans transporting missile components from a Pyongyang plant to the Dongchang facility where they made an unsuccessful attempt to launch a rocket in April.
Satellite photos taken on November 23 by DigitalGlobe Inc. showed that the North has conducted the same types of work there as those spotted before the April test.
"Given the observed level of activity noted of a new tents, trucks, people and numerous portable fuel/oxidizer tanks, should North Korea desire - it could possibly conduct its fifth satellite launch event during the next three weeks," the Colorado-based company said Monday on its website.
Rep. Ileana Ros-Lehtinen, chairwoman of the US House Foreign Affairs Committee, slammed the North for its reported missile preparations, calling it "unacceptable".
"We cannot be fooled again by a dictatorship that diverts all of its resources to building a nuclear arsenal at the expense of its own people," she said in a statement released Tuesday.
"We must impose strict sanctions on Pyongyang to cut off its financial resources and tighten the noose on those who assist the regime's weapons proliferation efforts."
The US government, however, said it has no "new information" on any progress in the North's preparations for a long-range ballistic missile.
"We would, of course, again, take this opportunity to remind the DPRK of the UN Security Council statement of April, which explicitly demanded that the DPRK not proceed with any further launches using ballistic missile defence technology," Victoria Nuland, spokesperson of the US Department of State, said in a briefing on Tuesday.
She was referring to North Korea's official name, the Democratic People's Republic of Korea.
Seoul's Foreign Ministry also declined to confirm intelligence matters.
"We're closely watching related movement in North Korea and having discussions with concerned partners," spokesman Cho Tai-young said earlier in the day.
With concerns mushrooming, Seoul is intensifying vigilance at home and diplomatic efforts to better guard against any urgency.
Lim Sung-nam, the Foreign Ministry's special representative for Korean Peninsula peace and security affairs, is leaving for Beijing on Thursday to meet his Chinese counterpart Wu Dawei and other officials. The missile issue is expected to top the agenda.
Vice Foreign Minister Ahn Ho-young held a two-day strategic dialogue with his Chinese counterpart Zhang Zhijun in Beijing early this week.
Deputy Foreign Minister Kim Kyou-hyun is also in Washington for regular consultations with officials including Kurt Campbell, assistant secretary of state for East Asian and Pacific Affairs.
In recent months, the North Korean regime has been stepping up propaganda campaigns in an apparent attempt to sway the South's December 19 poll, fanning concerns over a fresh provocation.
In September, South Korean patrol vessels fired warning shots at six North Korean crab boats to force them back. A series of other fishing boats briefly crossed the Northern Limit Line, the de facto maritime borders between the two countries.
"(North Korean leader) Kim Jong-un will continue to cement power and maintain his hard-line stance toward the South. Domestically, he will continue to strengthen control and monitoring to clam complaints." Defence Minister Kim Kwan-jin told a Tuesday meeting with 150 military commanders and senior officials.