North Korea appears to be preparing to hold a large-scale military parade to mark October's 75th anniversary of the founding of the ruling Workers' Party.

South Korea's Defense Ministry said on Monday in a report to the parliamentary defense committee that North Korean troops are continuing activities to prepare for events to mark the anniversary on October 10.

The ministry said that new buildings for storage were spotted under construction at the Mirim airfield in Pyongyang, a possible sign the North could showcase an intercontinental ballistic missile (ICBM) or a submarine-launched ballistic missile (SLBM) on the anniversary.

The ministry said that the five megawatt reactor in the North's nuclear plant in Yongbyon remains suspended and no unusual movement has been detected near the Punggye-ri nuclear testing site.  

However, it assessed that the activities of people, equipment and vehicles are continuing at missile facilities, hinting that North Korea is continuing development of short, middle, and long-range missiles.