I mean of course it's propaganda. The military would have no need (or desire) to disclose this publicly otherwise. But what really matters is whether or not it's true; are there really reversible attacks on US satellites, or is this just saber-rattling and trying to pre-sell US citizens on a new enemy?

I have no idea if it's real or not, but it sounds plausible, at least the passive attacks. It's mere speculation, though, that this can or will escalate to physical, irreversible attacks.

I think it's also likely that the US is conducting the same kinds of reversible attacks on adversaries' satellites, too. Or at the very least, we have the capacity to do so, and have tested it on our own gear.