Earlier on Monday, South Korean MPs demanded to know from Unification Minister Ryoo Kihl-Jae whether reports of heightened activity near the Punggye-ri nuclear test site in North Korea were correct.
The lawmakers were concerned because the JoongAng Ilbo newspaper had quoted a South Korean government official as saying: "There are recent active movements of manpower and vehicles at the southern tunnel at Punggye-ri. We are monitoring because the situation is similar to behaviour seen prior to the third nuclear test. We are trying to figure out whether it is a genuine preparation for a nuclear test or just a ploy to heap more pressure on us and the United States."
Replying to the queries of the MPs, Ryoo Kihl-Jae admitted that "there are such signs". Surprisingly, he later averred that he does not remember making the statement.
Kim Min-seok, spokesman of the South Korean defence ministry, told newspersons here on Monday that North Korea had built two tunnels at Punggye-ri but it is not clear which of them will be used.
Pointing out that so far "there had been no unusual movements that indicated (North Korea) wanted to carry out a nuclear test", Kim Min-seok said: ""The situation remains the same. If the North makes a decision, it could always carry out an atomic test."
The last time Pyongyang opted for an underground nuclear explosion on Feb 12, the international community "strongly condemned" the test. Members of the United Nations Security Council decided to "augment the sanctions regime". Even North Korea's key ally China advised the Kim Jong-un regime to "stop any rhetoric or acts that could worsen situations and return to the right course of dialogue and consultation as soon as possible".
However, Pyongyang was upset by the annual US-South Korea military drills in March and started issuing threats against both the countries. A few days ago, North Korea moved two mid-range rockets to its east coast and reportedly deployed them on mobile launchers.