WASHINGTON >> President Donald Trump’s order allowing Attorney General William P. Barr to declassify any intelligence that sparked the opening of the Russia investigation sets up a potential confrontation with the CIA, including over the possible implications for a person close to President Vladimir Putin of Russia who provided information to the CIA about his involvement in Moscow’s 2016 election interference.

The concern about the source, who is believed to be still alive, is one of several issues raised by Trump’s decision to use the intelligence to pursue his political enemies. It has also prompted fears from former national security officials and Democratic lawmakers that other sources or methods of intelligence gathering — among the government’s most closely held secrets — could be made public, not because of leaks to the news media that the administration denounces, but because the president has determined it suits his political purposes.

Trump granted Barr’s request for sweeping new authorities to conduct his review of how the Trump campaign’s ties to Russia were investigated. The president ordered the CIA and the other intelligence agencies to cooperate, granting Barr the authority to unilaterally declassify their documents and thus significant leverage over the intelligence community.

This afternoon, Trump, heading to his helicopter on the beginning of a trip to Japan, defended his decision and said the declassification would be sweeping. “What are we doing, we are exposing everything,” he told reporters. “We are being transparent.” He expressed no qualms about any national security implications.

Intelligence officials have feared before that their findings were being twisted to political agendas — notably concerns during the run-up to the Iraq War that information about Saddam Hussein’s alleged weapons of mass destruction was being cherry-picked to justify combat. But Trump’s decision is different.

It allows Barr, who has used the charged term “spying” to describe efforts to investigate the Trump campaign, sole discretion to declassify the intelligence behind the FBI’s decision to begin investigating whether any Trump aides or associates were working with the Russians. It also raises the specter that officials ranging from the FBI to the CIA to the National Security Agency, which was monitoring Russian officials, will be questioned about their sources and their intent.

The order could be tremendously damaging to the CIA and other intelligence agencies, drying up sources and inhibiting their ability to gather intelligence, said Rep. Adam Schiff, D-Calif., chairman of the House Intelligence Committee.

“The president now seems intent on declassifying intelligence to weaponize it,” Schiff said in an interview.

Trump has long held that he was a target of the “deep state,” at various points accusing former President Barack Obama without evidence of tapping his phones, the FBI of secretly trying to undermine his candidacy and past intelligence chiefs of bending their findings to prove Russian involvement in his election victory.

He has repeatedly appeared to side with Putin’s contention that there is no evidence of a Russian campaign to sabotage the 2016 election, even though the Mueller report left no question that the Russian leadership was behind both the theft and publication of emails and other data from Democrats and a social media campaign that ultimately worked to boost Trump’s candidacy, as well as efforts to tamper with election registration systems.

But it is the human source that particularly worries some former and current intelligence officials. Long nurtured by the CIA, the source rose to a position that enabled the informant to provide key information in 2016 about the Russian leadership’s role in the interference campaign.

John O. Brennan, the CIA director under Obama, would bring reports from the source directly to the White House, keeping them out of the president’s daily intelligence briefing for fear that the briefing document was too widely disseminated. Instead, he would place them in an envelope for Obama and a tiny circle of aides to read.

The source provided evidence for one of the last major intelligence conclusions that Obama made public before leaving office: that Putin himself was behind the Russia hack.

John Sipher, a former CIA official who led Russia operations for the agency, expressed concern that giving the president names of sources or agency officials who oversaw those informants could put those secrets at risk because they would inevitably be more widely disseminated.

“If the president of the United States asks for a name, it would be hard not to provide a name,” Sipher said. “It wouldn’t do him any good unless he sent it around to people to look into it, and that is where the security problem is, obviously.”

Schiff pledged that his committee would pay close attention to all of Barr’s actions in the inquiry.

“We are going to expose any abuse, any politicization of intelligence,” he said.

© 2019 The New York Times Company