It was not immediately clear what was tested, but the Korean Central News Agency (KCNA) reported that the test would bolster North Korea’s “reliable strategic nuclear deterrent.”
The launch occurred at around 10:45 p.m. local time (8:45 a.m. ET) Friday, according to KCNA.
In a statement provided to CNN, South Korea’s Ministry of Defense said it was working with United States intelligence agencies to monitor activity in areas of interest, but was unable to “confirm specifics.”
“The research successes being registered by us in defense science one after another recently will be applied to further bolstering up the reliable strategic nuclear deterrent of the Democratic People’s Republic of Korea,” KCNA said in a report Saturday.
The commercial satellite imagery, which was captured by Planet Labs, showed new activity at Sohae Satellite Launching Station and the presence of a large shipping container at the facility’s engine test stand, according Jeffrey Lewis, director of the East Asia Nonproliferation Program at the Middlebury Institute, which works in partnership with the imaging company.
While engine tests are considered to be less provocative than those involving missiles or satellites, Lewis said that the activity at Sohae is a significant development and a step toward weapons launches of a more threatening nature.
In November, North Korea fired two projectiles that were “presumed to be fired from a super-large caliber multiple rocket launcher,” South Korean army officials said.