Federal authorities believe China-backed cybercriminals may have attempted to tap into phones or networks used by former President Donald Trump and Sen. JD Vance, multiple sources familiar with the matter confirmed to CBS News. Officials are concerned the hackers could have infiltrated telecommunication systems and then targeted the candidates, the sources said.

The breadth of the potential cyber operation and what information the alleged hackers might have compromised remains unclear. The sources said the campaign was recently alerted that phones used by the candidates may have been among the targets of a cyber campaign.

The news was first reported by the New York Times.

The Justice Department and the FBI declined to comment. The Trump campaign declined a request for comment by CBS News. 

A source familiar with the investigation told CBS News the potential targeting of Trump and Vance was part of a broad cyber attack that targeted officials from both major political parties and law enforcement recently notified potential victims. Law enforcement is currently treating the hack as an act of espionage, not as an attempt at campaign influence, another source said.