Satellite imagery shows North Korea is upgrading its old launch site in the secretive country's northeast to handle larger rockets, like space launch vehicles and intercontinental missiles, a US institute claimed Tuesday.
The US-Korea Institute at Johns Hopkins School of Advanced International Studies said the upgrade of the Musudan-ri site began last summer and reflects North Korean determination to expand its rocket program.
The US and other nations are worried such rockets could be developed to deliver nuclear weapons.
North Korea on Tuesday vowed to push ahead with its nuclear program because of what it called US hostility. The international community is pressuring North Korea to refrain from conducting what would be its third nuclear test, following a failed attempt in mid-April to launch a satellite into space.
That launch, using its biggest rocket to date, the Unha-3, was from more sophisticated site at Sohae on the country's northwestern coast.
An April 29 aerial image of Musudan-ri on the opposite coast shows the initial stages of construction of a launch pad and rocket assembly building that could support rockets at least as big as the Unha-3, the institute told The Associated Press. A crane is visible where the launch pad is being built 1.1 miles (1.8 kilometers) from the old one. At the current pace of construction, the facilities should be operational by 2016-2017, the institute said.
"This major upgrade program, designed to enable Musudan-ri to launch bigger and better rockets far into the future, represents both a significant resource commitment and an important sign of North Korea's determination," said Joel Wit, editor of the institute's website, 38 North.
The institute says the assembly building shows similarities to one at the Semnan launch complex in Iran, which has a long history of missile cooperation with North Korea. But, officials there say it's premature to conclude the two nations cooperated in designing the new facility.
South Korea's National Intelligence Service said Tuesday said it cannot comment on whether it has detected any new activity at the Musudan-ri launch site.
The upgrade could be of particular concern to Japan, as rockets launched from the site in the past have flown east over that country. The flight path from Sohae heads south over the Pacific Ocean in the direction of Southeast Asia, avoiding Japan and South Korea.
The April rocket launch drew UN Security Council condemnation, as the launch violated an existing ban. Similar technology is used for ballistic missiles. The North, however, is not believed to have mastered how to wed a nuclear device to a missile.
The top US envoy on North Korea, Glyn Davies, who is meeting this week with counterparts from Japan, South Korea and China, warned Monday that the North conducting an atomic test would unify the world in seeking swift, tough punishment. Both of its previous nuclear tests, in 2006 and 2009, followed rocket launches.
A separate analysis of satellite images of a site that North Korea has used for its nuclear tests suggests it has ramped up work there over the past month. James Hardy, IHS Jane's Asia-Pacific specialist, said in a statement that there has been heightened activity at the northeastern Punggye-ri site, including mining carts, excavation equipment and a large amount of debris taken from inside a tunnel and piled around its entrance. The most recent image was from May 9.
In its statement Tuesday, in which North Korea vowed to push ahead with its nuclear program, it made no direct threat of a nuclear test and said it was open to dialogue. An analyst, Koh Yu-hwan at Seoul's Dongguk University, said the statement, from the North's Foreign Ministry, was a message that "the US should come to the dialogue table (with North Korea) if it wants to stop its nuclear test."
The 2006 and 2009 long-range rocket launches that preceded the North's previous nuclear tests were from Musudan-ri. Citing earlier satellite imagery of the site, the US-Korea Institute said land-clearing for the new facilities there began in the fall, and work has proceeded at a fast pace for eight months.
The latest image, from a commercially operated satellite, shows four concrete footings on one side of the launch pad that appear to be for a gantry that would prop up a rocket at launch. It has bigger dimensions than the gantry at the more sophisticated launch site at Sohae.
On another side of the launch pad there is a deep "flame trench" to capture the blast from a launched rocket. Slightly further away, on either side of the launch pad, are two separate buildings designed to enclose the fuel and oxidizer tanks that would funnel propellant into the rocket.
Satellite imagery also shows that about 70 homes, five larger buildings and many sheds in the nearby village of Taepodong have been razed and foundations laid for a large T-shaped structure that appears intended for assembling rockets. A road is under construction that would lead from this building to the launch site, 1.2 miles (1.9 kilometers) away.
The building's dimensions are larger than at the comparable structure at Sohae, and the existing one at Musudan-ri, the institute said.