US federal agencies have launched a criminal investigation into the public release of documents said to detail CIA hacking tools, US officials say.
They told US media that the FBI and CIA were co-ordinating the inquiry after Wikileaks published thousands of files.
These carried claims that the CIA had developed ways to listen in on smartphone and smart TV microphones.
The CIA, FBI and White House have declined to comment on the authenticity of the files leaked on Tuesday.
A CIA spokesperson told the BBC on Wednesday: "The American public should be deeply troubled by any Wikileaks disclosure designed to damage the intelligence community's ability to protect America against terrorists and other adversaries.
"Such disclosures not only jeopardise US personnel and operations, but also equip our adversaries with tools and information to do us harm."
On Wednesday, the US officials - who spoke on the condition of anonymity - told US media that the criminal investigation was looking into how the files came into Wikileaks' possession.
The inquiry would also try to establish whether the disclosure was a breach from inside or outside the CIA, the officials added.
The CIA has not confirmed whether the documents - said to date between 2013 to 2016 - are real.
But one of its former chiefs was concerned by their publication.
"If what I have read is true, then this seems to be an incredibly damaging leak in terms of the tactics, techniques, procedures and tools that were used by the Central Intelligence Agency to conduct legitimate foreign intelligence," ex-CIA director Michael Hayden told the BBC.
"In other words, it's made my country and my country's friends less safe."(Source: BBC)