WASHINGTON — The anti-secrecy organization WikiLeaks said Tuesday that it has obtained a vast portion of the CIA’s computer hacking arsenal, and began posting the files online in a breach that may expose some of the U.S. intelligence community’s most closely guarded cyber weapons.

WikiLeaks touted its trove as exceeding in scale and significance the massive collection of National Security Agency documents exposed by former U.S. intelligence contractor Edward Snowden.

A statement from WikiLeaks indicated that it planned to post nearly 9,000 files containing code developed in secret by the CIA to steal data from targets overseas and turn ordinary devices including cell phones, computers and even television sets into surveillance tools.

The authenticity of the trove could not immediately be determined. A CIA spokesman would say only that “we do not comment on the authenticity or content of purported intelligence documents.”

WikiLeaks indicated that it obtained the files from a current or former CIA contractor, saying that “the archive appears to have been circulated among former U.S. government hackers and contractors in an unauthorized manner, one of whom has provided WikiLeaks with portions of the archive.”

“At first glance,” the data release “is probably legitimate or contains a lot of legitimate stuff, which means somebody managed to extract a lot of data from a classified CIA system and is willing to let the world know that,” said Nicholas Weaver, a computer security researcher at the University of California.

Faking a large quantity of data is difficult, but not impossible, he noted. He said he knows of one case of WikiLeaks deliberately neglecting to include a document in a data release and one case of WikiLeaks deliberately mislabeling stolen data, “but no cases yet of deliberately fraudulent information.”

U.S. officials also allege WikiLeaks has ties to Russian intelligence agencies. The Web site posted thousands of e-mails stolen from Democratic party computer networks during the 2016 presidential campaign, files that U.S. intelligence agencies concluded were obtained and turned over to WikiLeaks as part of a cyber campaign orchestrated by the Kremlin.

U.S. intelligence officials appeared to have been caught off-guard by Tuesday’s disclosure. One U.S. official said that investigators were only beginning to look at the files being posted online, and declined to say whether the CIA had anticipated the leak or warned other agencies.

“We’ll see what it is whenever they release the codes,” the official said.

WikiLeaks said the trove was comprised of tools — including malware, viruses, trojans and weaponized “zero day” exploits — developed by a CIA entity known as the Engineering Development Group, part of a sprawling cyber directorate created in recent years as the agency shifted resources and attention to online espionage.

The digital files are designed to exploit vulnerabilities in consumer devices including Apple’s iPhone, Google’s Android software and Samsung television sets, according to WikiLeaks, which labeled the trove “Year Zero.”

WikiLeaks said the files were created between 2013 and 2016, and that it would only publish a portion of the archive – redacting some sensitive samples of code — “until a consensus emerges on the technical and political nature of the CIA’s program.”

Beyond hacking weapons, the files also purportedly reveal information about the organization of the CIA’s cyber directorate, with an organization chart and files that indicate that the agency uses the U.S. consulate in Frankfurt, Germany as a hub of digital operations in Europe, the Middle East and Africa.

Though primarily thought of as an agency that recruits spies, the CIA has taken on a larger role in electronic espionage over the past decade. CIA efforts mainly focus on so-called “close in” operations in which the agency at times relies on individuals to implant code on computer systems not connected to the Internet.

The CIA’s focus is more narrow and targeted than that of the NSA, which is responsible for sweeping up electronic communications on a massive scale around the globe.

The Washington Post’s Ellen Nakashima contributed to this report.