China targeted and might have held for months access to the infrastructure used to do wiretaps on the AT&T and Verizon networks.
This is a huge "told you so" moment for the cryptographic community that has been saying that such infrastructure does present a huge risk to national security. China reportedly used this capability for intelligence collection, obviously without a warrant ...
https://www.wsj.com/tech/cybersecurity/u-s-wiretap-systems-targeted-in-china-linked-hack-327fc63b?st=C5ywbp&reflink=desktopwebshare_permalink