China, Taiwan, Japan, and Trade Question

[Hermitian]

I am not exactly sure if this qualifies as a FACTUAL question or not because I don’t quite understand territorial waters, and treaties, etc.

From this Atlantic article (Bolding mine):

“Despite its limited international presence it is difficult to overstate Taiwan’s strategic importance to both the United States and an increasingly assertive China. The island’s location, economy, and security are all essential to American interests, and if Taiwan were to become part of China, as Beijing has insisted it must, China would instantly become a Pacific power, control some of the world’s most cutting-edge technologies, and have the ability to choke off oil shipments to Japan and South Korea—leverage it could use to demand the closure of U.S. military bases in both countries. In effect, Beijing would likely be able to achieve its goal of forcing the U.S. out of Asia. It is no surprise, then, that Taiwan is one of the rare issues on Capitol Hill today with bipartisan agreement—Congress has been regularly passing pro-Taiwan legislation with unanimous support throughout the Donald Trump era.”

What? If China took Taiwan, why would they be able to choke off oil shipments to South Korea or Japan and demand US base closures? I don’t see how holding Taiwan would greatly improve their ability to do this.

Taiwan is hundreds of miles away from these. There is hundreds of miles of China closer to Japan and South Korea than Taiwan.

Am I not understanding something or is this just bunk?

[Velocity]

Yes, that part is largely exaggeration. If China captured Taiwan, it could stop all international shipping going through the Taiwan Strait itself, but not the international shipping that could just re-route a few hundred kilometers to the east and still get to South Korea and Japan anyway. Sure, China could still send warships to maraud shipping there, but it doesn’t need to capture Taiwan first to do that anyway.