Japan's Defense Ministry now says North Korea fired one ballistic missile in mid-October, correcting its initial report that the North launched two.
The ministry on Tuesday released the results of its analysis of the launch on October 19.
Officials said one of the two missiles that the ministry initially reported was a new type of submarine-launched ballistic missile. They said the missile performed "pull-up maneuvers" in flight, changing its trajectory from a descending path to an ascent.
The officials said the other one was not a ballistic missile. They said an advanced warning radar system detected a man-made object moving through the space by accident, and determined that it was a ballistic missile.
The ministry stressed that the mistaken identification was a very rare occurrence, and that it will continue to focus on surveillance and intelligence gathering. It said it will review its operations, and make an effort to improve its capabilities to prevent a recurrence.