The Yomiuri Shimbun reported on September 27, quoting Japanese government sources, that North Korea’s preparations to launch a Rodong ballistic missile and the explosion observed in the northern part of the country earlier this month were coincidental.

According to the sources, reconnaissance satellite images taken earlier this month showed that North Korean military units were assembling at several locations, including a ballistic missile base, in the eastern part of the country.

The moves did not look initially significant. However, they were expanded to 10 sites across the nation. Communications that experts suspected were from the Rodong missile base in Shinori, north of Pyongyang, were also detected.

It was also reported that the Japanese government noted that the movement of military units appeared to be linked to the timing of the huge blast in the northern part of the nation on September 9.

An official from the Japanese Defense Agency analyzed that the moves may have been part of a full-scale military exercise since North Korea’s army, navy, and air force had shown unusual levels of activity up to that point.