The AG is just grandstanding in this case, and while it might play well domestically, on the international stage it is a mistake.
First, the grand jury had no business returning an indictment, which must find sufficient evidence that:
1. A crime was committed.
2. The accused did it.
3. The court has jurisdiction.
It fails on predicates (1) and (3). To have criminal jurisdiction the act would have to either be committed on U.S. soil, or committed by a non-state actor, as an act of piracy. Clearly, the perpetrators were state actors, and committed the acts outside U.S. soil, so the alleged act was perhaps an act of war, but not a crime over which any U.S. court would have criminal jurisdiction.
Contrary to current practice, the locum jurisdiction of a criminal act is the location of the actor when he acted irreversibly (“committed”), not the location where any harm might have occurred.
Even if committed on U.S. soil, unless it was on the territory of a federal enclave, the Constitution confers no authority to make the alleged act a crime, unless it can be considered piracy, and that only if done by nonstate actors.
Last I checked, China does not elect members to the U.S. Congress to make laws for Chinese territory. The government of the U.S. is not the government of the world.
This indictment only makes the U.S. look silly in the eyes of the world, and to anyone with even a rudimentary knowledge of the law of nations as of 1787. From contacts with members of the DoJ, it would seem that no one there has a clue on that subject.