China has installed powerful radars with a detection range of 3,000 km so they can spy on South Korean and Japanese military maneuvers, Chinese media reported Monday.

The move comes amid a spat with Seoul over the stationing of a Terminal High-Altitude Area Defense battery from the U.S. here whose powerful radar Beijing fears could be used to spy on its own military activities.

The reports said China installed an Over The Horizon or OTH radar in Inner Mongolia in January. Unlike conventional radar signals that pass through the atmosphere, OTH signals bounce off of the earth's ionosphere 100 to 450 km above the surface to detect targets 3,000 km away.

The THAAD radar as currently configured will only have a range of 800 km, though that can be adapted with a software switch.