North Korea may be preparing to conduct a new rocket engine test at its Sohae space centre, according to satellite images taken between 25 November and 31 December 2017.

Some media outlets speculated that the satellite images showed activities related to a possible satellite launch but, experts at 38North believe constructions underway at the test site indicate "preparations for a future test".

The images from 23 November 2017 and 25 December 2017 reportedly show new tire tracks at the vertical engine test stand and a new structure under construction near the launch pad.

A rail-mounted environment shelter was also moved from close to the vertical engine test stand to the concrete apron. The environment shelter was likely moved either to prepare rocket engines prior to testing or to unload the engines after a test.

"Both color and near-infrared imagery, however, show no indications that an engine test has taken place since November 23, suggesting that if the current activity is test related, it is likely preparations for a future test," 38North experts wrote in a report.

"Alternative explanations for these activities include normal maintenance and repair or propaganda activity to reinforce recent official North Korean statements concerning space exploration and Kim Jong Un's 2018 New Year's address," the report added.

Around 50m southeast to the launch pad, a new structure is being constructed, which resembles an office complex. The proximity to the launch pad could indicate that it is related to launch operations support.

"Construction of what appears to be a guard barracks 1,000 m northwest of the launch pad is complete with fish ponds, greenhouses and gardens. At the Horizontal Processing Building, a small (15 m by 5 m) structure that has been under construction since August 2017 is complete and several small vehicles or shipping crates have been observed there on occasion," 38North experts said.

The report also mentioned the presence of several small vehicles near the main facility entrance and checkpoint, and near the administration and headquarters buildings.

All the activities put together are indicators of an upcoming rocket engine test, the report noted.

Since 2012, Pyongyang has used the Sohae test site to launch all its satellites. Based on the satellite images, some media outlets speculated the regime was prepping up to launch its new Kwangmyongsong-5 Earth-observation satellite.

The North Korean dictator, who has made known his ambitions of becoming a nuclear power in the world, reportedly also aspires to dominate the space exploration market in future.