The fun part is they don't know the extent of the comprise or how long it has been going on.
What happened is that CISA recently published a report stating that they think a lot of US telecommunications equipment has been compromised. It isn't a one time breach. They know that China has control over a unspecified amount of critical components. The malware China is using is extremely complex and very hard if not completely impossible to detect. China is very good at covering there tracks so even getting a sample of Malware is hard.
Because of all this, CISA is now recommending that people use encrypted messagers.
Lol.
Seven years ago I spent hours trying to explain to my MP that this would happen if they weakened encryption and put in back doors.
He seemingly couldn't get his head round the fact that you have to assume foreign adversaries have access to everything in transit and they're not going to be worried about longer prison sentences designed to make up for weaker security.
I should send him an email asking if he understands the argument now it's coming from an American in a suit and not just one of the plebs.
You absolutely should
Also include links to the human rights abuse done by the Chinese police. And the fact that South Korea almost just turned into a dictatorship.