China’s about the same size - landmass wise - as the US. However, about 70% of their population lives within 100 miles of the Eastern coast. It’s VERY high density, much higher than the US, and a LOT more dense than the old USSR.
The remaining population is predominantly agricultural, and in Western China. Not much in the way of big industry, technology, OR government installations once you get outside the strip along the Eastern seaboard of China.
78% of U.S. Population lives near the West, North or East coasts California, Oregon, Washington, Michigan, Illinois, Indiana, Ohio, Maine, Vermont, New Hampshire, Massachusetts, Rhode Island, Connecticut, New York, Pennyslvania, New Jersey, Delaware, D.C. Maryland, Virginia, North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, and most of Texas.
Most of that 78% would be killed by twenty nuclear detonations: Seattle, Portland, San Francisco, Los Angeles, San Antonio, Houston, Fort Worth, New Orleans, Mobile, Tampa, Atlanta, Miami, Winston-Salem, Norfolk, Washington D.C., Philadelphia, New York City, Boston, Chicago, Detroit.