The Wall Street Journal reported that the so-called Salt Typhoon breach may have potentially provided the Chinese government access to systems the federal government uses for court-authorized network wiretapping requests, which could undermine US intelligence gathering efforts.
"While we appreciate that there may be an ongoing federal investigation into this matter, and we appreciate your cooperation with any such inquiries, we cannot wait to fortify our defenses," the letter said. "Accordingly, we respectfully request a closed-door briefing from appropriate representatives of each of your companies regarding the reported Salt Typhoon breach."
The US lawmakers are asking each of the three companies to describe when their companies first became aware of the breach and what countermeasures have been taken to reinforce protections of the systems the US government uses for wiretapping requests.
The panel is also open to recommendations from the companies about what Congress and the federal government can do to bolster security against government-backed cyberattacks.