The National Security Agency has implanted software in nearly 100,000 computers around the world that allows the United States to conduct surveillance on those machines and can also create a digital highway for launching cyberattacks.

WASHINGTON — The National Security Agency has implanted software in nearly 100,000 computers around the world that allows the United States to conduct surveillance on those machines and can also create a digital highway for launching cyberattacks.

While most of the software is inserted by gaining access to computer networks, the N.S.A. has increasingly made use of a secret technology that enables it to enter and alter data in computers even if they are not connected to the Internet, according to N.S.A. documents, computer experts and American officials.

The technology, which the agency has used since at least 2008, relies on a covert channel of radio waves that can be transmitted from tiny circuit boards and USB cards inserted surreptitiously into the computers. In some cases, they are sent to a briefcase-size relay station that intelligence agencies can set up miles away from the target.

The radio frequency technology has helped solve one of the biggest problems facing American intelligence agencies for years: getting into computers that adversaries, and some American partners, have tried to make impervious to spying or cyberattack. In most cases, the radio frequency hardware must be physically inserted by a spy, a manufacturer or an unwitting user.

The N.S.A. calls its efforts more an act of “active defense” against foreign cyberattacks than a tool to go on the offensive. But when Chinese attackers place similar software on the computer systems of American companies or government agencies, American officials have protested, often at the presidential level.

Among the most frequent targets of the N.S.A. and its Pentagon partner, United States Cyber Command, have been units of the Chinese Army, which the United States has accused of launching regular digital probes and attacks on American industrial and military targets, usually to steal secrets or intellectual property. But the program, code-named Quantum, has also been successful in inserting software into Russian military networks and systems used by the Mexican police and drug cartels, trade institutions inside the European Union, and sometime partners against terrorism like Saudi Arabia, India and Pakistan, according to officials and an N.S.A. map that indicates sites of what the agency calls “computer network exploitation.”

“What’s new here is the scale and the sophistication of the intelligence agency’s ability to get into computers and networks to which no one has ever had access before,” said James Andrew Lewis, the cybersecurity expert at the Center for Strategic and International Studies in Washington. “Some of these capabilities have been around for a while, but the combination of learning how to penetrate systems to insert software and learning how to do that using radio frequencies has given the U.S. a window it’s never had before.”

How the N.S.A. Uses Radio Frequencies to Penetrate Computers

The N.S.A. and the Pentagon’s Cyber Command have implanted nearly 100,000 “computer network exploits” around the world, but the hardest problem is getting inside machines isolated from outside communications.

Transmission distance of up to eight miles

DATA FROM TARGET COMPUTER

TARGET

COMPUTER

DATA TRANSMITTED

BACK TO N.S.A.

Data and malware are transmitted

over a covert radio frequency

MALWARE

ANTENNA

CASE

N.S.A. FIELD

STATION

TRANSCEIVER

PLANTED INSIDE

USB CABLE

1. Tiny transceivers are built into USB plugs and inserted into target computers. Small circuit boards may be placed in the computers themselves.

2. The transceivers communicate with a briefcase- size N.S.A. field station, or hidden relay station, up to eight miles away.

3. The field station communicates back to the N.S.A.’s Remote Operations Center.

4. It can also transmit malware, including the kind used in attacks against Iran’s nuclear facilities.

No Domestic Use Seen  ( RIGHT!!!!!!!!!!!!!!!!!!! )

There is no evidence that the N.S.A. has implanted its software or used its radio frequency technology inside the United States. While refusing to comment on the scope of the Quantum program, the N.S.A. said its actions were not comparable to China’s.

“N.S.A.'s activities are focused and specifically deployed against — and only against — valid foreign intelligence targets in response to intelligence requirements,” Vanee Vines, an agency spokeswoman, said in a statement. “We do not use foreign intelligence capabilities to steal the trade secrets of foreign companies on behalf of — or give intelligence we collect to — U.S. companies to enhance their international competitiveness or increase their bottom line.”

Over the past two months, parts of the program have been disclosed in documents from the trove leaked by Edward J. Snowden, the former N.S.A. contractor. A Dutch newspaper published the map of areas where the United States has inserted spy software, sometimes in cooperation with local authorities, often covertly. Der Spiegel, a German newsmagazine, published the N.S.A.'s catalog of hardware products that can secretly transmit and receive digital signals from computers, a program called ANT. The New York Times withheld some of those details, at the request of American intelligence officials, when it reported, in the summer of 2012, on American cyberattacks on Iran.

President Obama is scheduled to announce on Friday what recommendations he is accepting from an advisory panel on changing N.S.A. practices. The panel agreed with Silicon Valley executives that some of the techniques developed by the agency to find flaws in computer systems undermine global confidence in a range of American-made information products like laptop computers and cloud services.

Embracing Silicon Valley’s critique of the N.S.A., the panel has recommended banning, except in extreme cases, the N.S.A. practice of exploiting flaws in common software to aid in American surveillance and cyberattacks. It also called for an end to government efforts to weaken publicly available encryption systems, and said the government should never develop secret ways into computer systems to exploit them, which sometimes include software implants.

Richard A. Clarke, an official in the Clinton and Bush administrations who served as one of the five members of the advisory panel, explained the group’s reasoning in an email last week, saying that “it is more important that we defend ourselves than that we attack others.”