North Korea is gearing up for the massive military exercise that will be held in October.
The South Korean ministry said missiles, armoured vehicles, multiple rocket launchers and other weapons had been collected at the Mirim military airfield for a rehearsal, three months before the 70th anniversary of the founding of the North's ruling Workers Party on October 10.
In February, the North Korean party adopted a resolution calling for a "grand style" military parade in October. It emphasized the need for hardware to boost the country's fighting capacity.
The last such event was held in July 2013, an intimidating, two-hour spectacle of military might and patriotic fervour, involving wave after wave of goose-stepping soldiers, tank batteries and missile launchers.
The parades have been carefully watched for glimpses of any new hardware that might signal a new step in the North's military development.