While Russia claims the object is a “space apparatus inspector,” its behavior has been unlike any other object with a similar purpose, including others already deployed by Moscow, according to Yleem D.S. Poblete, the assistant secretary of the U.S. Bureau of Arms Control, Verification and Compliance. American officials “are concerned” about the satellite, Poblete told the attendees at the Conference on Disarmament in Geneva on Aug 14.

“We don’t know for certain what it is and there is no way to verify it,” Poblete said. “But Russian intentions with respect to this satellite are unclear and are obviously a very troubling development, particularly, when considered in concert with statements by Russia’s Space Force Commander, who highlighted that ‘assimilating new prototypes of weapons into [Russia’s] Space Forces’ military units is a ‘main task facing the Aerospace Forces Space Troops.'”

The United States has been warning about Russia’s pursuit of space weapons for years. Russian Ministry of Defense officials have confirmed repeatedly since 2009 that Moscow is developing anti-satellite weapons. In February last year, Russia said it was developing an anti-satellite missile. In March this year, the Russian Defense Ministry announced that its space troops received “a mobile attack anti-satellite system.”

The space weapons push by Moscow continues amid claims by Russian Minister of Foreign Affairs Sergey Lavrov that “prevention of an arms race in outer space” is a priority for Russia. Meanwhile, the abnormal behavior by the space object could be in violation of a draft treaty on space weapons being promoted by Russia, Poblete said.

“The United States has clearly articulated the many flaws of this draft treaty,” Poblete said. “We also note that, understanding unusual, even potentially threatening behavior, where a satellite is observed doing something that is contrary to what its owners claim it is intended to do, is of great concern to us.”

Alexander Deyneko, a senior Russian diplomat in Geneva, dismissed what he called “the same unfounded, slanderous accusations based on suspicions, on suppositions and so on.”

“We are seeing that the American side are raising their serious concerns about Russia, so you would think they ought to be the first to support the Russian initiative. They should be active in working to develop a treaty that would 100 percent satisfy the security interests of the American people,” he said.

“But they have not made this constructive contribution,” he said.

China’s disarmament ambassador Fu Cong called for substantive discussions on outer space, leading to negotiations.

“China has always stood for peaceful use of outer space and we are against weaponization of outer space, an arms race in outer space, or even more turning outer space into a battlefield,” he said.

Poblete’s warning comes on the heels of a U.S. Department of Defense report to Congress with recommendations on how to create a new military branch dedicated to warfighting in space. In a speech at the Pentagon timed with the release of the report last week, Vice President Mike Pence cautioned that Russia, China, North Korea, and Iran have been working on anti-satellite weapons for years.

President Donald Trump ordered the Pentagon to create the space force report, as he has pushed Congress for months on the creation of the new military branch. The White House is already working on a bill with lawmakers.

“The space environment has fundamentally changed in the last generation,” Pence said. “What was once peaceful and uncontested is now crowded and adversarial. Today, other nations are seeking to disrupt our space-based systems and challenge American supremacy in space as never before.”

Pence also pointed out that Russia and China are carrying out highly sophisticated space activities that could bring their satellites close to American space systems, “posing unprecedented new dangers.”

Since taking office, Trump has issued three space policy directives, revived the National Space Council, and outlined a comprehensive national space strategy.

“When it comes to defending America, it is not enough to merely have an American presence in space. We must have American dominance in space,” Trump said on June 18.

Poblete said that the draft “Treaty on the Prevention of the Placement of Weapons in Outer Space, the Threat or Use of Force against Outer Space Objects” is the wrong mechanism for achieving nonproliferation of space weapons. Poblete noted that Russia may have already circumvented the treaty since there is no way to verify the nature of its recently launched space object.

“It is a flawed document, proposed by a country that has routinely violated its international commitments,” Poblete said.

***Reuters contributed to this report.