With the war of words between the US and North Korea showing no signs of subsiding, growing attention is being focused on what Kim Jong-un's next move will be.
North Korean Foreign Minister Ri Yong-ho on Sept. 21 said Pyongyang may detonate a hydrogen bomb in the Pacific Ocean, during his visit to New York to attend the annual UN General Assembly. This came in response to US President Donald Trump's earlier threats that the US could "totally destroy" North Korea if it refuses to halt its provocations against the nation and its allies.
However, experts here are sceptical that North Korea will conduct a nuclear experiment any time soon due to lack of infrastructure.
"The recent 'natural earthquakes' detected in North Korea are viewed as aftershocks of its recent nuclear experiment at Punggye-ri," Go Myong-hyun, analyst at the Asan Institute for Policy Studies told The Korea Herald.
"This shows that the underground test has weakened the ground at Punggye-ri, and using the venue is the most logical option for them at the moment," he said.
North Korea's latest and sixth nuclear test on Sept. 3 was conducted at the North's key nuclear test of Punggye-ri, some 460 kilometers from Seoul. The South Korean Meteorological Administration said the test caused an artificial earthquake of magnitude 5.7, while the US Geological Survey and the Chinese government measured a seismic activity of 6.3.
On Sept. 23 the Comprehensive Nuclear-Test Ban Treaty Organisation under the UN detected two natural earthquakes of magnitude 2.6 and 3.2, which are presumed to be aftershocks of North Korea's earlier underground nuclear test. This was later confirmed by the KMA here.
Reuters recently reported that testing a nuclear-tipped missile over the Pacific Ocean would be a "logical final step by North Korea" to prove the success of its weapons programme. But it said the move would be "extremely provocative and carry huge risks," citing an arms expert here.
It also quoted a US expert as saying that an atmospheric nuclear test was unlikely for now due to its substantial technical and diplomatic risks and that a full-range ICBM test is likely to come first.
"For now, North Korea's most realistic option for such provocation would be a missile launch," said Go. "The problem is that in order for Pyongyang to maintain the current level of tension it has built, something 'bigger and better' need to come up. However, that will also bring uncertainties and a bigger price tag," he added.
The task of further upgrading the defence line along its borders also seems to be on Kim's agenda.
In New York, Ri said that the US had declared war on his home country, and warned that US military aircraft would be shot down should they approach North Korea airspace. His statement was believed to target the Sept. 23 US Air Force exercise coupled with US President Donald Trump's speech.
It is clear the North Korean regime viewed the operation as a heightened threat, as it quickly bolstered its military defence along the flight path of US bombers.
The South Korean parliamentary intelligence committee claimed that the Sept. 23 operation involving B-1B bomber and F-15 fighter jets was under Pyongyang's raider, citing Seoul's spy agency. The National Intelligence Service here also said North Korean military took no measures in response around the time of the flight.
"North Korea relocated its warplanes and strengthened defences along the east coast," Lee Cheol-Woo, the chief of the National Assembly's intelligence committee.
Cheong Wa Dae and government officials here are closely watching the time frame of the next possible provocation.
Seoul's National Security Adviser Chung Eui-yong reportedly told South Korean President Moon Jae-in on Wednesday that the probability of action by Pyongyang was most likely around Oct. 10 and 18, during a meeting among leaders of the ruling and opposition parties.
Oct. 10 marks the 72nd anniversary of the founding of its ruling Workers' Party of Korea, while China's 19th Communist party leadership elections is slated to take place on Oct. 18. North Korea has often conducted military provocations around the time of such political events.
South Korea's Foreign Minister Kang Kyung-wha said that there is a "very high possibility" that North Korea may launch additional military provocations, during an interview with cable channel JTBC on Thursday.
"South Korea and the US are bracing for various types of possible provocations through close collaboration," Kang said.
"Both nations are currently cooperating to have full preparedness and strong deterrence against whatever types of provocations," she said, adding that the specifics of the plan are classified.