Those China-specified US Ohio class boomers are stationed in the Hawaii, while those Russia-specified are patrolling in the Atlantic coast.
To target China from the Atlantic coast means that you will have to reduce the payload of your D5 missiles.
Less payload means fewer warhead.
Warheads were already reduced because of START treaty. And I can tell you for a fact that the Trident boats can currently hit China from the Atlantic Ocean with its current payload. And they are not based in Hawaii.