WASHINGTON, Dec. 2 (UPI) -- North Korea is digging a new tunnel at a nuclear test site, raising fears of a continued buildup of nuclear weapons by Kim Jong Un, who was dubbed a "forgotten maniac" by Sen. Cory Gardner, R-Colo., on Tuesday.
Satellite images from Nov. 2 analyzed on 38 North, a Johns Hopkins University website dedicated to North Korea issues, indicated North Korea was excavating a tunnel for nuclear testing at Punggye-ri nuclear test site.
Three existing tunnels already serve as test sites. The East Portal at Punggye-ri served as the site of Pyongyang's first nuclear test in 2006, but currently does not appear maintained, according to Jeffrey Lewis. The North Portal, used for tests in 2009 and 2013, continues to show signs of activity and the South Portal is still under construction, the analyst wrote.
In September, analysts Jack Liu and Joseph S. Bermudez, Jr., wrote that an area in the South Portal Area dug before 2012 had been widened and "graded" with differently colored sand or gravel.
The new tunnel, Lewis wrote, provides access to Mount Musan and could be another entrance to an underground facility designed to test multiple nuclear explosions. The main tunnel, where all entrances converge was the site of nuclear tests in 2009 and 2013.
Tunneling in the mountain can be dangerous. Too many tests could weaken the rock in the mountain, Lewis wrote, and many branches could stress the capacity of the mountain to contain nuclear explosions.
On Tuesday, Sen. Cory Gardner raised the issue of North Korea nuclear proliferation in The Wall Street Journal, stating, "It is time for the U.S. to counter this forgotten maniac."
"North Korea is a proliferator that has tested nuclear weapons on three separate occasions in violation of multiple U.N. Security Council resolutions. This past weekend it test-fired a ballistic missile from a submarine. That attempt failed, but Mr. Kim will try again," Gardner wrote.