China last week conducted a test of a maneuvering satellite that captured another satellite in space during what Pentagon officials say was a significant step forward for Beijing’s space warfare program.

The satellite capture took place last week and involved one of three small satellites fitted with a mechanical arm that were launched July 20 as part of a covert anti-satellite weapons development program, said U.S. officials familiar with reports of the test.

One official described the satellite-grabbing spacecraft as a "mobile satellite launch vehicle."

A Pentagon spokeswoman declined to comment on the specifics of the test. But Cynthia O. Smith, the spokeswoman, confirmed that the satellites, designated Payloads A, B, and C, have maneuvered in space since their launch.

"The United States Strategic Command’s Joint Functional Combatant Command for Space (JFCC-Space), consistent with its routine operations to maintain track of objects in space, has monitored these satellites since their launch and has noticed the relative motions of these satellites amongst each other and with respect to other space objects," she said.

The Pentagon’s website Space-Track.org does not report on missions or functions of the hundreds of space objects it tracks, and Smith referred further questions to the Chinese government.

A Chinese Embassy spokesman did not return emails seeking comment on the ASAT test.

The satellites involved in the space warfare development program were identified by the Chinese as "scientific experimentation satellites," according to a notice published July 24 in the online journal Space News.

They were identified as Chuangxin-3 (Innovation-3), Shiyan-7 (Experiment-7), and Shijian-15 (Practice-15). The spacecraft with the robotic mechanical arm that conducted the satellite capture experiment has not been authoritatively identified from among the three orbiters. However, space analysts suspect it is Shiyan-7.

Space News is published by the China Aerospace Science and Technology Corp. (CASC), which builds strategic missiles and space launchers, and China Aerospace Science and Industry Corporation (CASIC), China’s largest missile manufacturer.

The notice stated that the three satellites were launched atop a Long March-4C rocket on July 20 from the Taiyuan Satellite Launch Center in north central China.

"These three satellites are to be used for the observation of space debris and conducting scientific experiments in space maintenance techniques like space arm operations," the statement said.

Space Track continues to identify the satellites as by their payload designations, rather than using the Chinese names.

Space analyst Bob Christy, who writes the blog Zarya.info that first disclosed the three satellites, said no public information has indicated the three satellites involved in earlier close maneuvers engaged in a significant orbit change since activities in August.

"There have certainly been no more approaches between them, and Payload A has shown no sign of maneuvering in the whole of its time in space," he said in an email.

Since no other satellites are in the same orbit as the three satellites and another satellite known as Shijian-7, "if the capture was last week, it didn't involve any of these working together," he said.

Christy said that leaves the possibility that Shijian-7 was captured by Payload C during a close flyby around Aug. 17.

"My actual calculations showed them getting closer than 500 meters but given the inherent error margins of the Space Track data, I stuck with a few hundred meters," he said.

Another possibility is that the test involved a detachable part of one satellite and its release into a separate orbit, and the subsequent recapturing of the component using the extension arm, Christy said.

"If the separation distance was small and the period of separated flight was short, then U.S. sensors are unlikely to have detected an extra object in orbit," he said.

A third possibility is that the test involved completely different satellites that were not observed by non-government space trackers.

Christy’s analysis of the August activities revealed that the satellites conducted several experiments.

Since August, Payload C and Shijian-7 showed slight variations in orbit that are likely the result of thruster operation for position control, Christy stated in a recent blog post.

In August, Payload B, a non-maneuvering satellite, was positioned about 620 miles behind Payload C, a spacecraft that specialists say could be the craft with the manipulator arm, and Payload C gradually slowed to until is passed very close to the other satellite.

The robotic satellite may be part of efforts to develop China’s large space station set to be deployed around 2020.

However, Pentagon officials believe the small satellite activity is more closely associated with China’s secret ASAT program.

Little is known about the Chinese space warfare program, which is among the Chinese military’s most closely guarded secrets.

China conducted a direct ascent ASAT missile test in January 2007 that destroyed a Chinese weather satellite and created tens of thousands orbiting debris pieces that threaten both manned and unmanned spacecraft.

Chinese officials have told U.S. counterparts that the 2007 test was a one-time event and so far have not conducted further debris-causing satellite attack tests.

A U.S. official told the Free Beacon in August that the launch of the three satellites was part of Beijing’s covert anti-satellite warfare program.

The official said the craft with the robotic arm was viewed as the most threatening because U.S. satellites, vital strategic assets used by both the American military and civilian infrastructure, are vulnerable to kinetic or electronic disruption in space.

The official said the satellites are part of China’s "Star Wars" space weapon program that has been largely ignored by the Obama administration over concerns that pressing China to explain its space weapons would upset U.S.-China relations.

The ASAT program is a "real concern for U.S. national defense," the official said.

Until the satellite capture, the mission of the spacecraft with the mechanical arm was unknown. It was thought that it could used to grab, gouge, or alter the orbits of other satellites.

The craft also could be used for maintenance and repair.

Rick Fisher, a Chinese military affairs specialist, said the robot-arm satellite that he believes is the Shiyan-7 is part of China’s dual-use space program that includes satellites for military close-surveillance and attack missions. Civilian applications include development of space manipulator arm technology.

"As an ASAT, a future version of the SY-7 could be used to take close-up images of U.S. satellites, to remove systems from those satellites and return them to China, to directly damage U.S. satellites or to plant ‘mines’ on those satellites or close nearby," said Fisher, with the International Assessment and Strategy Center.

"An SY-7-like ASAT gives China the option to attack enemy satellites without creating a large cloud of debris that may also damage other Chinese satellites."

Fisher said China recently hosted a major space conference and is seeking to position itself as a space "superpower" as a means to increase cooperation and technology acquisition from other countries.

At the conference, "Chinese officials made a deliberate appeal to Canada, which developed and built the manipulator arm used on the International Space Station and U.S. Space Shuttles," Fisher said.

However, Fisher said China made every effort to conceal the People’s Liberation Army’s role in the space program and would probably deny any military role in the developing mechanical arm technology for offensive space operations.

"The ‘Canadarm’ [manipulator arm] was developed in Canada with Canadian funding and four were purchased by NASA for the U.S. Space Shuttle program," he said.

China conducted a test launch of a new high-Earth orbit anti-satellite missile called the DN-2 in March, according to U.S. officials.