(CNN) North Korean state media has reported that "another crucial test" was successfully conducted at the country's Sohae Satellite Launching Ground late Friday.

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 test 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 White House has seen reports of the test and is "coordinating closely" with Korean and Japanese allies, a senior US administration official confirmed to CNN.