Springboard: Book 3 by Tom Clancy
A top secret Pentagon wargame is hacked. Only Net Force has the expertise to track down the culprit, but they are tied up with other priorities. Due to shifting budget priorities, Net Force is moved onto the DoD budget. That means that as a military operation, they can now give top priority to the Pentagon's problem. They soon make a connection between the attack and a Chinese general in Macau. But this investigation is too big for Net Force and they are forced to work with members of Cybernation, the virtual reality nation which has opposed Net Force in the past.