single B2 with a bunker buster could destroy the 3 gorges dam and China would be in the same shoes

No, China wouldn't be in the same shoes. Not even close. The Three Gorges Dam currently provides less than 1% of China's total electricity demand. Yet, China consumes more than twice the electricity of the United States. China's annual electricity consumption recently surpassed the combined total of the EU, Russia, India, and Japan. Let that sink in.

could destroy the 3 gorges dam and China would be in the same shoes

No it won't. Not even close. The Three Gorges Dam currently provides less than 1% of China's total electricity demand. Yet, China consumes more than twice the electricity of the United States. China's annual electricity consumption recently surpassed the combined total of the EU, Russia, India, and Japan. Let that sink in.