The statement is in line with a recent report by WSJ in October, which said a China-backed threat actor, tracked by Microsoft as Salt Typhoon, has hacked into US internet service provider (ISP) networks to steal sensitive US data and establish persistence.

Queries sent to CISA for further details on the investigation did not elicit a response until the publishing of this article.

Affected telcos likely include AT&T, Verizon

While the FBI held out on more technical details of the investigation, adding “our understanding of these compromises to grow as the investigation continues,” WSJ had reported that three leading US broadband providers — AT&T, Lumen Technologies, and Verizon Communications — may have been affected.