The site is seen as a critical element in Pyongyang's quest to build a missile capable of delivering a nuclear weapon across the Pacific.
The satellite pictures were taken during the past month. Most significantly, the photographs reveal a completed launch umbilical tower at Tongchang-dong
Tim Brown, an image analyst who is a senior fellow at Global Security.org
, says it has taken North Korea about a decade to finish the facility.
"Little by little, they've been getting closer and closer to having an operational site. We can now say, I think confidently, that the launch tower and the launch pad are basically finished," said Brown. "And the question is do they have a launch vehicle that's ready to be launched? And we just don't know."
Brown and a colleague first spotted the facility in 2008, when it was still under construction,. They were the first to publicly reveal it.
Brown says it is a more advanced operation than North Korea’s first launch site, at Musudan-ri
, because it has a rocket engine test stand, missile assembly and test buildings, a launch bunker and an observation tower.
"A sophisticated launch site like this is amazing. Compared to the old site, which was nothing more a place they go when the weather was right to launch their missiles," Brown added. "This is actually a dedicated launch center."
Daniel Pinkston is the senior analyst in Seoul for the International Crisis Group
. He says the facility is a major step in North Korea's quest for an intercontinental ballistic missile that can strike the United States.
"They’re basically inseparable. If you have a space launch capability you can turn that into an ICBM relatively easily, at that point," said Pinkston.
U.S. Defense Secretary Robert Gates warned last month that North Korea is within five years will have the capability to strike North America with a missile.
Pyongyang has tested two nuclear weapons and says it has turned some of its stockpile of plutonium into bomb material. There are concerns that it aims to create a nuclear bomb that can be carried on a missile.
Because the new launch site neighbors China, along the Yellow Sea, it will be difficult for other countries to conduct surveillance of pre-launch testing and actual launches.
North Korea has never publicly referred to the new launch site
. That may change as leader Kim Jong Il prepares to turn over the country to his son, Kim Jong Un.
Impoverished North Korea has vowed to become a "strong and prosperous" country by next year. Some regional analysts say part of that campaign could include another attempt to launch a three-stage missile.
Previous attempts have failed.
The last launch, along with a nuclear test in 2009, prompted the United Nations to impose tough new sanctions on Pyongyang.
ICG analyst Pinkston says Pyongyang knows another launch could drive a wedge between the parties to the stalled six-nation talks about its nuclear weapons ambitions.
"I think it’s pretty clear that the Chinese, the Japanese, the U.S., the South Koreans and the Russians, for that matter, are all going to have slightly different views on this. You are going to have different threat perceptions. You’re going to have different ideas on how it should be dealt with," stated Pinkson. "So this really serves into North Korean hands. And, so, I won’t be surprised if it [a launch] happens this year."
Since North Korea already is under strict sanctions, it is not clear what more could be done to punish it, should it attempt another missile launch or nuclear weapons test.
Some analysts say a launch from the new facility might also be intended to pressure Washington into direct talks with Pyongyang, something the North Korean leadership has desired for decades. Washington, however, wants a multilateral approach to North Korea, involving its neighbors.