WASHINGTON — A never-before-seen missile photographed last month on a Russian MiG-31 interceptor is believed to be a mock-up of an anti-satellite weapon that will be ready for warfare by 2022, three sources with direct knowledge of a U.S. intelligence report say.

The Russian anti-satellite weapon, which is attached to a space launch vehicle, is expected to target communication and imagery satellites in low Earth orbit, according to one source, who spoke on condition of anonymity. For reference, the International Space Station and the Hubble Space Telescope travel in low Earth orbit.

Images of the mysterious missile on a modified Russian MiG-31, a supersonic near-space interceptor, appeared in mid-September.

Initial testing of the mock system began in September and is slated to run through Wednesday, according to one of the sources. The tests, which are referred to as a "captive carry tests," are designed to evaluate the mock weapon during flight, according to the source.

"These are the types of tests you do first in order to gain confidence that the weapon and air frame are going to work together during flight," a source explained to CNBC, adding that the next testing milestone will occur in 2019.

The Russians are expected to conduct weapon releases tests next year, when the mock system is to be launched from the belly of the aircraft. What's more, sources with direct knowledge of the U.S. intelligence report expect the weapon to join the Kremlin's arsenal by 2022.

"My take is, as I understand it, it is possible that this is an anti-satellite system," said Pavel Podvig, director of the Russian Nuclear Forces Project. He said Moscow has previously worked on such systems. "It seems like a capability that would be sort of nice for them to have," he said, noting that China and the U.S. have developed similar weapons.

"The concept of air-launched kinetic anti-satellite weapons has been around for a very long time and has been demonstrated over the years by the Chinese, Russians, and by us," Thomas Karako, director of the Missile Defense Project at the Center for Strategic and International Studies, told CNBC while looking at images of the missile.

"Having said that, the Russians have of course lots and lots of sensational press releases about [Russian President Vladimir] Putin's new toys, so a little bit of skepticism is in order," Karako added.

While anti-satellite missiles are by no means new, the latest revelation comes less than eight months after Putin touted his nation's growing military arsenal.

"I want to tell all those who have fueled the arms race over the last 15 years, sought to win unilateral advantages over Russia, introduced unlawful sanctions aimed to contain our country's development: You have failed to contain Russia," Putin said during a national address in March.

The image in this article was republished with permission by Ship Sash.