A Chinese hacking campaign potentially gained access to data on hundreds of thousands of cell phone users in America, including top U.S. leaders.

Officials believe at least eight telecom companies were compromised in China's cyber operation which has been dubbed "Salt Typhoon."  

Sen. Mark Warner, vice chair of the Senate Intelligence Committee, is calling it the worst telecom hack in U.S. history.

China's communist regime was able to grab data including the location of phone users, who they spoke with and when, even targeting a small group of senior government officials, and in some cases able to read text messages and listen to conversations.

The FBI is telling consumers to use encrypted apps, including for text messages and voicemail.

The U.S. believes the hackers gained access to communications of senior U.S. government officials and prominent political figures. But Deputy National Security Adviser Anne Neuberger said, "We don’t believe any classified communications has been compromised.” 

Neuberger said the impacted companies are still working to resolve the breach of their data, but none of them "have fully removed the Chinese actors from these networks."

"So there is a risk of ongoing compromises to communications. Until U.S. companies address the cybersecurity gaps, the Chinese are likely to maintain their access," Neuberger said.

Federal authorities confirmed in October that hackers tied to China targeted the phones of Donald Trump and his running mate, Sen. JD Vance, along with people associated with Democratic candidate Vice President Kamala Harris.