WASHINGTON (AP) -- Construction to upgrade North Korea's main rocket launch pad should be complete by this fall, allowing Pyongyang to conduct a launch by year's end if it decides to do so, a U.S. research institute said Thursday.
The U.S.-Korea Institute at the Johns Hopkins School of Advanced International Studies is basing its conclusions on commercial satellite imagery of the Korean west coast site of Sohae. The latest photo is from Aug. 8.
The institute says construction is nearing completion at the launch pad to handle larger rockets than the Unha-3 that was blasted into space from Sohae in December 2012.
North Korea has worked rapidly to expand the launch tower, and has progressed on a railway to access it. It also has completed external work on two prominent, domed buildings at the site whose function is uncertain.
The Associated Press was provided with the analysis ahead of publication on the institute's website, 38 North.
It remains unclear whether North Korea is planning another long-range rocket launch, and whether it yet has an operational rocket that would require the much bigger launch tower.
A major construction program has been underway at Sohae since mid-2013. North Korea says the Unha-3 was part of a peaceful space program, but the U.S. is concerned the technology could put the North closer to having a ballistic missile that can reach America.
North Korea hasn't tested a long-range rocket or nuclear device in the past year and a half, but has conducted an unusually high number of weapons tests during 2014, including short-range missiles.
Last week, it fired five rockets into the sea. Tensions on the divided Korean Peninsula could escalate as U.S. and South Korea began military exercises this week that Pyongyang objects to.
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