Satellite imagery shows North Korea has erected a tented city and mobilized hundreds of trucks and armored vehicles in preparation for a massive military parade marking the 70th anniversary of the ruling party.

The U.S.-Korea Institute says military units, which began mobilizing in May, have been practicing at a mock-up of the venue for Saturday's parade and mass rally.

The institute's website 38 North says photos taken Tuesday show about 800 tents, and more than 600 trucks and 200 armored vehicles at a former air base in the east of Pyongyang.

The likely centerpiece of the parade, ballistic missile launchers, can't be seen yet, but seven drones are visible on mobile launchers.

The parade is expected to be North Korea's biggest spectacle since Kim Jong Un took power.