Senate Intelligence Committee Chair Mark Warner says he's stunned by the scope of China's breach into the U.S. telecommunications system, which went further than was described by the Biden administration.

"The barn door is still wide open, or mostly open," the Virginia Democrat told The New York Times on Thursday. "We've not found everywhere they are."

The Chinese hackers, which Microsoft named Salt Typhoon, have been able to monitor Americans' cell phone calls and texts, including those made by people such as President-elect Donald Trump and Vice President-elect J.D. Vance.