Local media on Monday reported that Pyongyang may be preparing for its fourth nuclear test, citing movements at the Punggye-ri test site in its northeastern tip. The speculation grew even further after Unification Minister Ryoo Kihl-jae told lawmakers that there was an increase in the movements near the complex, which was used for past three nuclear tests.
"Vehicles and personnel have showed movements near the southern tunnel at the Punggye-ri site, but they are seen as normal activities," ministry spokesman Kim Min-seok said.
The impoverished communist nation carried out its third nuclear test on Feb. 12 and has threatened nuclear strikes against the U.S. and South Korea in response to tougher U.N. sanctions imposed for its provocative test and the joint military drills held in the South by the allies.
"Following the third nuclear test, we had explained that the North made both the western and southern tunnels ready for a nuclear test," Kim said. "The situation remains the same. If the North makes a decision, it could always carry out an atomic test."
The sprawling nuclear test site is known to have three tunnel entrances and multiple support buildings.
Last week, Defense Minister Kim Kwan-jin told lawmakers that intelligence authorities detected activity near the southern tunnel of the Punggye-ri test site following the Feb. 12 underground test at its northwestern tunnel.
However, an in-depth analysis is needed to figure out whether the activity indicates preparations for another test or is normal, Kim said, noting that South Korea has pledged to destroy the North`s nuclear facilities if there is a sign that a nuclear attack is imminent.
The latest move comes after Pyongyang last week said it would resume operations at its mothballed Yongbyon nuclear complex, which would allow the North to extract plutonium from spent fuel rods. The nation`s main nuclear reactor was shut down under an agreement reached at nuclear disarmament-for-aid talks in 2007.
South Korean and U.S. have stepped up their intelligence efforts to detect signs of a potential missile launch as the North was last week seen moving two medium-range missiles to its east coast.
Amid mounting tensions, the Pentagon on Sunday announced its plan to delay a planned intercontinental ballistic missile (ICBM) test in an apparent move to avoid stoking tensions with North Korea, which has warned diplomats to consider evacuating from Pyongyang.
The defense ministry said it has been "calmly" responding to the communist rivals` warlike rhetoric in an attempt to cool tensions with Pyongyang.
"The U.S. made a decision to delay the ICBM test not to give cause for the North to provoke," spokesman Kim said. "Our military is calmly observing the North`s movement."