A special North Korean train that last month took a long-range missile to a west coast launch site has recently made a journey to another launch site on the east coast, a report said on Wednesday.
South Korea and the United States are wondering whether Pyongyang intends simultaneous launches from both sites or whether the train's latest journey is just a smokescreen to confuse watchers, Seoul's Chosun Ilbo newspaper said.
The paper said the train was used in May to transport a missile to a newly-completed site at Dongchang-ri on the northwest coast.
It said the train was also recently spotted travelling from a missile research centre in Pyongyang to Musudan-ri on the east coast, which the North used for its three previous long-range missile launches.
The paper quoted a South Korean government source for its information. The National Intelligence Service declined comment on what it called intelligence matters.
On Tuesday Chosun said the North has installed a launch structure and completed a hangar at Dongchang-ri.
But it said no radar has yet been set up and no missile has been brought to the launch pad itself, meaning a launch is not imminent.
The North on April 5 staged what it called a satellite launch from Musudan-ri, using a Taepodong-2 rocket theoretically capable of reaching Alaska.
The US and its allies said the launch was a disguised missile test and the UN Security Council condemned the operation.
The North vowed to conduct more nuclear and missile tests unless the UN apologised, and went ahead with its second atomic test on May 25.
US and South Korean officials have said it may be preparing another ballistic missile test. And US intelligence officials have been quoted as saying it may also stage a third nuclear test.
Chosun said Pyongyang appears to have three to four intercontinental ballistic missiles, and may be keeping one or two of them at the research centre in the capital.