North Korea has installed a screen over the entrance to one of the test tunnels at its nuclear test site in Kilju County, North Hamkyung Province, inhibiting intelligence gathering activities and raising fears of an impending nuclear detonation.

A government source explained today, “It is believed that a roof-shaped obstruction has been installed. It appears to be a measure to stop leaks of information on preparations for a nuclear test, which are currently in their final stages.”

A second source went on, “It is one way for North Korea to camouflage the nuclear test site. It resembles the tactic they used last December when they launched a long-range missile.”

The move comes after Jeong Seung Jo, the chairman of the Joint Chiefs-of-Staff, told reporters yesterday, “Signs of bustling movement have been captured at Punggye-ri in Kilju County, North Hamkyung. We cannot release specific details at this time, but we are watching closely to see if their behavior is intended to be deceptive or if it is really to prepare for a nuclear test.”

"When they launched the long-range missile they performed some acts of deception," he went on, "but it is hard to tell now because what they are doing is underground."

Meanwhile, a U.S. nuclear submarine and one Aegis cruiser have also arrived in South Korea. The 6,900-ton Los Angeles class submarine ‘USS San Francisco’ is currently in port at Jinhae, while the 9,800-ton Aegis cruiser ‘USS Shiloh’ is at Busan.

Although both South Korea and the U.S. say that the vessels are in Korea to participate in joint drills, and have nothing to do with North Korean nuclear testing, many analysts are unconvinced.

Mixed messages don’t help. One military official emphasized, “Even though this joint drill was planned ahead, it will also send North Korea a warning message that there will be no ignoring its wrongdoings.”

However, an official with the Joint Chief of Staff rejected the claim, saying, “This drill is part of an annual training plan and has nothing to do with North Korean nuclear issues.” A U.S. military official agreed, declaring, “The visit to South Korea by a nuclear submarine was planned a long time ago. Do not try to associate this with the nuclear issue.”