The revelation comes more than two months after Russian President Vladimir Putin called “invincible” the growing hypersonic arsenal that Moscow has been putting together in the last three decades.
Avangard, the hypersonic glide vehicle Russia is currently working on, is designed to be located on top of an intercontinental ballistic missile, and can sail on top of the atmosphere thanks to aerodynamic forces.
The weapon is said to be able to travel at least five times the speed of sound, and can obliterate targets even without being outfitted with explosive just by packing enough force through prevision and speed.
Thomas Karako, director of the Missile Defense Project at the Center for Strategic and International Studies, told CNBC: “These kinds of boost glide vehicles attack the gaps in our missile defence system.
“There’s no time like the present to modify our current missile defence posture.
“It is unfortunate that we have let Russia come this far.”
Russia has already conducted three known tests on the weapon between 2016 and 2017, the sources revealed, and is expected to conduct a fourth one this upcoming summer.
A US intelligence report said during the tests, some vehicles were mounted to Russian-made SS-19 intercontinental ballistic missiles, while one featured a mock warhead, the sources said, leading to think the weapon can also carry a nuclear warhead.
The Avanguard could also be equipped with onboard countermeasures that are able to defeat even the most advanced missile-defence systems, the sources added.
If Russia were to achieve the initial operational capability of this new weapon by 2020, it would step ahead of both China and Russia in the military race.
Mr Putin boasted about Kremlin’s hypersonic nuclear weapon arsenal in March, during a state of the nation address.
Speaking about the Avanguard, he said the weapon is capable of reaching targets at a speed of 20 times the speed of sound and strike “like a fireball”.
Issuing a chilling warning, he added: “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.”
The US admitted earlier this year their forces are unable to shield against a hypersonic weapon.
Air Force General John Hyten, commander of US Strategic Command, told the Senate Armed Services Committee said: “We don’t have any defence that could deny the employment of such a weapon against us.
“Both Russia and China are aggressively pursuing hypersonic capabilities,” he added, noting that the US has “watched them test those capabilities.”