North Korea has upgraded security measures at a rocket launch station on its west coast over the past two years, presumably out of concern of intelligence leaks, 38 North, a think tank that follows developments in the communist county, said Friday.

According to a report by North Korean military affairs analyst Joseph Bermudez carried by 38 North, improvements to the outer perimeter of the Tongchang-ri launch site began around 2011 and proceeded slowly. Then it recently started picking up pace.

The launch site located in Cholsan, North Pyongan Province, is where North Korea launched a long-range missile in February.

It said the main perimeter was converted into a more capable security barrier with widened patrol paths and fences, according to the report.

In 2015, new guard positions were implements and an entrance on the outer perimeter was built, the analyst said, citing satellite imagery.

"Today, the outer security perimeter is 27 kilometers long, encompassing 28 square kilometers ... the inner security perimeter is 19 kilometers long," he said.

The upgrade may indicate that more scientists, engineers and technicians will occupy the launch facility, Bermudez said.

"Upgraded security measures may also reflect a growing North Korean concern of intelligence collection by foreign governments using defectors from the area or outside agents who may try to infiltrate the site to collect information," he noted. (Yonhap)