Taiwan has powerful radar pointed at much of China

Strategy Page:

When pressed, Taiwan will admit that their new early warning radar atop Leshan Mountain in central Taiwan is probably the most powerful such phased array radar in the world. American experts hint that while the Leshan radar may not be the most powerful, it is among the most powerful.

Taiwan put the Leshan radar into service in January 2013, and have been quite pleased with its performance. Not only can the radar spot missile launches up to 5,000 kilometers away, it can give Taiwan about six minutes warning of a Chinese missile attack. That’s enough to alert the missile defenses and Taiwanese defense installations. China has over 1,400 ballistic missiles within range of Taiwan, and any invasion attempt is expected to start with the launching of many, if not most, of these missiles.

Early warning of a Chinese missile attack is not what the Leshan radar is used for most of the time. No, much to the distress of China the Leshan radar can also keep track of most aerial activity over China. That 5,000 kilometers range of the Leshan radar pretty much covers most of China, not to mention North Korea and, well, you get the picture. The radar covers areas closer (than 2,000 kilometers) in even more detail, and this provides excellent coverage of most key Chinese military bases and weapons production facilities.

The Leshan radar has been under construction for a decade and costs $1.4 billion. The radar operates on a mountain over 3,000 meters (10,000 feet) high. Much of the equipment and building materials had to be flown in, and the climate up there is a lot colder than most Taiwanese are accustomed to. Putting the radar at such a high altitude gave it a clear view of eastern China. Despite Chinese objections, the United States provided much of the needed radar design data and some of the equipment.
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Presumably they share this information with the US.  I suspect that the radar will be a primary target in any Chicom attack on Taiwan.