The U.S. National Security Agency is reportedly intercepting Internet communications from U.S. residents without getting court-ordered warrants, in an effort to hunt down malicious hackers.

The previously undisclosed NSA program monitors Internet traffic for data about cyberattacks originating outside the U.S., according to a New York Times article published Thursday and based on leaks from former NSA contractor Edward Snowden.

President Barack Obama’s administration launched the NSA cybersecurity program without public notice or debate, according to the report.

Two mid-2012 memos from the U.S. Department of Justice allowed the NSA to target Internet traffic, including traffic inside the U.S., without getting warrants, the Times said. The DOJ allowed the NSA to monitor IP addresses and look for cybersignature patterns, although the NSA sought to target suspected hackers before it could establish links to foreign governments or crime groups.

The NSA and the U.S. Office of the Director of National Intelligence (ODNI) defended the agency’s cybersecurity role.

With cyberattacks on the U.S. increasing in scale and sophistication, “it should come as no surprise that the U.S. government gathers intelligence on foreign powers that attempt to penetrate U.S. networks and steal the private information of U.S. citizens and companies,” ODNI said in a statement. “These operations play a critical role in protecting U.S. networks from disruptive, and even destructive, cyberthreats.”

Government intelligence agencies use a “number” of legal authorities to gather intelligence about foreign organizations engaged in cyberattacks on the U.S., ODNI added. The Foreign Intelligence Surveillance Act allows intelligence agencies to target people “reasonably believed” to be outside the U.S., it said.

“The government cannot target anyone under the court-approved procedures unless there is an appropriate, and documented, foreign intelligence purpose,” ODNI added.

The NSA said it “plays a pivotal role in producing intelligence against foreign powers that threaten our citizens and allies while safeguarding personal privacy and civil liberties.”

All information acquired by the agency is “strictly handled and controlled,” the agency said in a statement. The data-handling procedures, approved by the U.S. attorney general, “do not simply limit the use or retention of information,” it added. “As importantly, they require NSA to limit the acquisition of U.S. person information in the first place.”

For data the NSA acquires under Executive Order 12333, a presidential surveillance directive dating back to 1981, the NSA generally cannot query communications content using U.S. identifiers such as a name or an email associated with a U.S. resident, unless the agency determines there are ties to a foreign intelligence purpose, the NSA said.

The undisclosed NSA program shows how the government can subvert civil liberties without public debate, said Bill Blunden, an IT security author and investigator.

The program is “a reminder that our legal framework can be countermanded in secret, and that this dynamic represents an existential threat to democratic governance,” he said by email.

This secrecy divides U.S. society into two groups, one with access to secret information and one without, he added. “This asymmetry undermines political participation as democracy necessitates a public that exercises sound judgement based on accurate information,” he said.

The NSA program was launched after the agency proposed using a warrantless surveillance program for cybersecurity, the Times report said. The agency received guidance on targeting cybersignatures from the U.S. Foreign Intelligence Surveillance Court.

After the DOJ tied the NSA’s cyberthreat surveillance to an existing program focused on monitoring foreign governments, the agency complained that those limits left a “huge collection gap against cyberthreats to the nation,” reported the Times, quoting an agency newsletter.