Viewers of China Central Television got an unusual glimpse last month of that nation’s cyber-weaponry: A video clip showed a military computer program on which an unseen user selects a “target” — in this case, a Falun Gong Web site based in Alabama — and hits a button labeled “attack.”

The video amounted to just six seconds in a state media documentary called “The Cyber Storm Has Arrived!” But it offered an uncommonly candid depiction of offensive cyber-capabilities developed by a country that is routinely accused of mounting attacks and just as routinely issues denials.

Later in the documentary, Col. Du Wenlong, a researcher at China’s top military research institute, argues that the country’s ability to attack and defend its networks “must be interwoven.” He adds, “To keep up with the pace of virtual technology, we must increase our fighting ability.”

For more than a decade, experts say, China has had a cyberwarfare capability, and in recent years, the nation has seemed intent on developing it — especially now that the United States has launched a Cyber Command to coordinate the military’s offensive and defensive capabilities. The countries have recently begun a dialogue to reduce tensions in cyberspace.

The 22-minute documentary featuring the clip includes images of the Pentagon, the White House and U.S. jets bombing targets as the narrator describes China as behind its adversaries in developing cyber-capabilities. Du describes several types of attacks that might be deployed in cyberwarfare, including “logic bombs,” software implanted in a foe’s network that later can be triggered to cause crucial systems to crash.

Western experts who viewed the clip — first reported by the Epoch Times, a news service affiliated with the Falun Gong, a spiritual movement that long has clashed with the Chinese government — said the military computer program featured in the video was not especially sophisticated and probably does not represent the state-of-the-art of Chinese cyber-capabilities. Yet the experts were struck by what appeared to be the first and most public indication from an official Chinese source that it has the ability and the intention to hit adversaries, even when their computer servers are based in other countries.

“Their official line is they’re innocent, ‘Why are you blaming us?’ ” said James A. Lewis, director of the Center for Strategic and International Studies’ technology and public policy program. In the clip, he said, “they were caught with their pants down.”

Chinese officials have long insisted that their national laws prohibit any disruption of computer networks. Yet when major cyberattacks have happened — against Google, Lockheed Martin, the Dalai Lama, the office of the German chancellor — U.S. analysts and some international authorities have blamed China.

Falun Gong

Between 1999 and 2001, China began cracking down on Falun Gong activists, whom they saw as a potential source of unrest, according to a 2002 Rand study. Falun Gong was banned in 1999 by the Chinese government, which declared it an “evil cult.” Since then, human rights activists say, many of its followers have been killed and thousands detained amid a decade-long crackdown.

The Chinese government has sent several members to prison for disseminating Falun Gong material on the Internet and routinely blocked access to Falun Gong Web sites, including “mirror” sites hosted on servers around the world, the Rand study says.

In the clip, the user is prompted to press a button to launch a “denial of service attack,” a tactic commonly used to temporarily disable Web sites by bombarding them with requests for access, causing servers to crash. Such operations, while sometimes just nuisances, can cause serious disruptions, such as ones in Georgia in 2008, amid conflict with Russia. The tactic was used against Falun Gong sites a decade ago, experts said.

The Internet address that appeared on the screen during the “attack” sequence in the video is registered to the University of Alabama at Birmingham. Officials there said that a student in 2001 hosted a Falun Gong Web site on the university server linked to that address but that the site was removed soon after.

Wang Baodong, a spokesman for the Chinese Embassy in Washington, declined to elaborate on the images in the video but said: “It’s no secret that Falun Gong and its subordinate institutions have been intensifying their subversive efforts against China in cyberspace. And China has every legitimate right to take action against such harmful activities to defend its national security interests.”

Erping Zhang, a spokesman for the Falun Gong Information Center in New York, said: “We have been experiencing constant hacking from China for many years. We knew it was being done, but we never knew it was to this extent with actual military resources devoted to attacking us. And to have that so openly admitted to the public on a CCTV report. It’s surprising and appalling.”

Zhang said Falun Gong has “no special activity in Alabama” not conducted elsewhere, but the group did have a second Web site that was hosted by a regional affiliate in the state. On the clip, the Web site for this group was listed as a possible target.

“The fact that they would even target a small club in Alabama gives us an idea how seriously they take the cyberwarfare,” he said.

Timing of documentary

The video aired two days after the July release of the Pentagon’s first cyber-strategy, which is focused on defense but which China has interpreted as a sign of new cyberspace aggression.

“The U.S. Department of Defense has announced that if other countries intentionally break into their computer systems, that constitutes an act of war, and they will return the favor,” the narrator says in an apparent reference to the Pentagon strategy. “The worldwide virtual network is now like a powder keg ready to go in a flash.”

Pentagon spokeswoman April Cunningham called this a mischaracterization of the U.S. military’s cyber-strategy. She said that under the administration’s international cyber-strategy, the United States “reserves the right to respond appropriately” to any threat to national interests.

State Department officials declined to comment on the clip, but its coordinator for cyber-issues, Christopher M. Painter, said, “A key part of our international strategy is to engage countries, including China, in building consensus around norms of appropriate state behavior in cyberspace.”

In the documentary, Du says that “online, there’s no front line” and urges listeners to mobilize as part of a “joint defense system of the military and the people.”

“So then,” he concludes, “we lay a good foundation for the cyberwar ahead.”

Staff researcher Liu Liu in Beijing contributed to this report.