The South Korean government has said the planned launch of a satellite by North Korea next month is being used as a cover to disguise a test for a nuclear missile delivery system.
The secretive state announced that the satellite will be launched into orbit in October, potentially to tie into the seventieth anniversary of the inception of the North Korean communist party on the 10th.
South Korean Foreign Minister Yun Byung-se subsequently made the allegations about the secret missile test which the United States said could lead to further sanctions.
North Korea says its space programme is peaceful and any attempt to stop it is an attack on its sovereignty.
The country launched a satellite into orbit in 2012, the Unha-3, that was said to be mounted with cameras to take images and transmit them back to the capital Pyongyang.
No signal has ever been detected from the device which German aerospace engineer Markus Schiller described as "low performance" and "not a game changer" in 2013.
Speaking this week, Schiller said that nothing since the previous launch has changed his assessment. "Most of these activities still seem to be more motivated by political reasons than by engineering ones," he said.
South Korea's defence ministry said this week it had not detected any signs of preparations at the main launch site, about 50 km from the Chinese border.
The Unha-3 was a three-stage rocket based on 1950s Soviet Scud missile technology, with advanced fuel used in its final stage.
Although the rocket was suitable to launch a satellite, it would make a poor vehicle to deliver weapons because launch preparations are difficult to hide due to the time it takes to assemble the rocket, stand it up and fuel it.
"Preparations for the Unha-3, and whatever new space launch vehicle they might roll out, will be observable well in advance of a launch," said Daniel Pinkston, a visiting fellow at Babes-Bolyai University in Romania.
However, although the Unha-3 is relatively unsuitable for military operations, Pinkston said: "It should be clear how important these capabilities are to the leadership because they are expensive and difficult to acquire.”