China uses all this Internet based theft to improve Chinese military capabilities, and weaken American ones. Department of Defense officials also see China's ambitious space program as another component of Chinese military strategy. By combining the ability to knock down American military satellites, while at the same time launching Internet based attacks at American military, government and commercial Internet activities, China believes it could make up for a lot of current American military superiority. At the very least, the Chinese believe that all this stolen (via the Internet) data and damage to American space satellites would cripple American military power aimed at China.
We don't know how well this will work, of course.
The problem is that it doesn't have to work that well or work for that long to be good enough.
As I've written many times, we are much more powerful than China. But China is much closer to potential theaters of war than we are. So China can gain local superiority for a period of time by striking first while we will need to defend our forward-deployed forces while the Chinese go after their objective, and reinforce our forward-deployed forces to overcome the Chinese surge.
China wants to win any fight before we can reinforce our forward-deployed forces (those that endure and survive the initial attacks).
So if Chinese cyber-war and anti-satellite efforts just degrade our forces even if we overcome their attacks and regain our pre-attack capabilities over time, China has bought the time. And they will have shocked us, inflicting a morale hit that may make us more cautious because we don't know what else they can do.
If China buys time and injects uncertainty into our minds, they might reach their objectives before we can gather our superior strength to counter-attack.