Chinese hacking effort is far more pervasive than previously reported, sources say

The Chinese effort to hack prominent Americans is far more pervasive than previously reported, ABC News has learned.

Sources told ABC News that U.S. law enforcement and intelligence officials are concerned the espionage operation by the Chinese government may have been in place for well over a year -- and perhaps longer -- before it was recently discovered.

The Chinese appear to have been able to gather large volumes of data in a sweeping covert campaign targeting the cellphones and mobile devices of business leaders and other high profile Americans of both political parties, according to sources familiar with the investigation.

The evidence is mounting that in some cases the Chinese operation was able to tap into, or get access to, what cellphone users of Verizon, AT&T and Lumen were communicating.

Authorities are trying to determine whether the Chinese were able to listen to conversations and watch text messages in real time, as they were occurring, or if they captured the material for review at a later time.

Sources said that U.S. officials are only beginning to understand the breadth of the Chinese operation, but what they have found so far is deeply concerning and represents a massive breach of privacy on a disturbing scale.

MORE | Cellphone of Trump's lead defense attorney compromised by Chinese hackers, sources say

The targets have included not only former President Donald Trump and Sen. JD Vance, but also individuals working in a number of government agencies.

The FBI is systematically contacting victims, sources said.

Salt Typhoon, the name given to an advanced, persistent threat actor run by the Chinese government, is believed to be behind the operation.

Intelligence officials suspect Salt Typhoon hackers exploited routers as a gateway to cellphones and mobile devices, and there is concern that Chinese capabilities for intrusion may have made significant advances.

In a statement issued last month, Verizon representatives said, "We are aware that a highly sophisticated nation-state actor has reportedly targeted several U.S. telecommunications providers to gather intelligence. Along with federal law enforcement, industry peers and third-party cyber experts, we have been and are working to confirm, assess and remediate any potential impact. Verizon is committed to assisting law enforcement in this investigation."

Representatives for AT&T and Lumen declined to comment

According to sources, the FBI determined that Blanche's communications with family and friends were compromised, and investigators are still trying to determine if communications with more sensitive contacts were impacted.

Sources have told ABC News that Blanche is potentially under consideration to become Trump's next White House counsel or to take on a senior law enforcement-related role under a new Trump administration.

The wide-ranging Chinese hacking operation made national headlines two weeks ago, when the FBI issued a statement saying it was investigating recently identified "malicious activity" by "actors affiliated with" the Chinese government who were targeting commercial telecommunications infrastructure.

The statement said the FBI and the Homeland Security department's Cybersecurity and Infrastructure Security Agency had been notifying victims of the operation. That apparently included private companies and individuals, who have subsequently beefed up their security measures and replaced compromised cellphones, according to sources.

ABC News previously reported that Trump and his running mate, Sen. JD Vance, were told last month that they and others associated with the campaign were among the victims whose cellphones were targeted. Democrats were also targeted, ABC News was told.

The FBI believes that the hackers were not able to access encrypted applications on the phones they targeted, but the investigation is still working to confirm that and identify further victims, according to sources.

Earlier this week, the Wall Street Journal reported that hackers linked to Chinese intelligence services compromised phone lines used by politicians and senior national security and policy officials across the U.S. government, allowing the hackers to "scoop up call logs, unencrypted texts and some audio from potentially thousands of Americans and others with whom they interacted."

Asked about the latest reporting from ABC News, a spokesperson for the FBI declined to comment.

Steven Cheung, a spokesperson for Trump, said in a statement, "Make no mistake, foreign adversaries are terrified of the strength and resolve of President Trump. President Trump will stand up against our enemies and defend the United States from any and all aggression. He will let nothing stop him or get in his way to fight for the American people and to Make America Great Again."

Blanche oversaw Trump's defense in the former president's weekslong criminal trial in New York, where a jury in May convicted Trump on 34 counts of felony fraud stemming from his role in falsifying business records to conceal hush-money payments to adult film star Stormy Daniels in order to boost his electoral prospects in the 2016 presidential election.

Sentencing is set for later this month, though it's unclear if that will still happen after Trump was reelected to the White House on Tuesday.

After Trump's conviction in May, Blanche told the Associated Press that Trump "knows there's a lot of fight left and there's a lot of opportunity to fix this and that's what we're going to try to do."