The DoD/OPM/FBI would not reveal who the attacker is at all. Think about this for a second, why the hell would they reveal the fact that they could attribute an attack to China? That stuff is kept secret because that's how the intelligence agencies work. The US has a global cybersecurity strategy and so they are setting the precedent that they can hold nations responsible for cyberattacks and this became apparent with the North Korea/Sony attack attribution debacle