The Taepodong-2 missile engine tested is not believed to represent a new, longer-range capability. The missile is estimated to have a range of about 2,500 miles, potentially threatening the western edge of Alaska. The range could be extended with engine improvements and light payloads.
The engine was tested on an engine test stand, a critical facility for measuring vibration from the engines and adjusting guidance systems to account for it. That can help make missiles more accurate.
State Department spokesman Sean McCormack would not confirm the test Tuesday but said that if one occurred it would violate a UN resolution banning North Korean tests of ballistic missiles and components.
"Any ballistic missile tests of the kind reported would not be permitted under 1718," McCormack told reporters.
North Korea set off a failed long-range Taepodong-2 space launch vehicle in 2006 from Musudan-ni. That test alarmed the world and gave new energy to the stop-and-start diplomacy over North Korea's nuclear program. It also conducted a surprise launch of a Taepodong-1 over Japan in 1998 from that East coast site. Pyongyang has not yet tried to launch the ballistic missile version of Taepodong-2.
A major South Korean newspaper, Chosun Ilbo, first reported the engine ignition test Tuesday, quoting an unnamed South Korea government official.
Construction of the North's new missile base on its West coast is about 80 percent complete, South Korean Defense Minister Lee Sang-hee told a parliamentary committee last Thursday. He said the ministry is keeping a close eye on its construction.
North Korea has quietly built the new missile base over the last eight years. It is larger and more capable than Musudan-ni, an older and well-known launch pad for intercontinental ballistic missiles.
The primary purpose of the facility is to test engines, a capability the Musudan-ni site does not provide. The launch pad has been operational since 2005 but has not yet been used. Joseph S.
Bermudez, Jr., the imagery analyst with Jane's Information group who first publicly identified the site, believes North Korea wants to use it to develop longer-range and more accurate ICBMs. It also could launch satellites into space. Multiple tests are difficult at Musudan-ni.
John Pike, an imagery analyst with GlobalSecurity.org, says the new facility represents a major step forward for North Korea's long-range missile program as it would allow multiple test flights in a short time.
North Korea is believed to possess up to a dozen nuclear warheads. The new launch pad would help in the development of missiles to carry them, he said. In 2006, North Korea conducted an underground nuclear test, removing any doubt it had the means to make a nuclear warhead. Its previous missile test showed it also had the means to deliver one.
North Korea has agreed in principle to forswear nuclear weapons and the plutonium used to fuel them. It placed its known plutonium-producing reactor out of commission earlier this year, but has recently backtracked by taking some equipment back out of storage in possible preparation to restart the reactor.
In June, North Korea destroyed the reactor's distinctive conical cooling tower as a symbolic show of good faith with the United States and other nations bargaining with it. But the deal has since stalled over North Korea's obligations to allow intensive international fact-checking of its past nuclear activities.
North Korea claims the U.S. has not held up its end of a nuclear disarmament deal because it has not removed the North from a list of state sponsors of terrorism.