WASHINGTON — Russia conducted another successful test of a hypersonic weapon system capable of carrying nuclear warheads, the Kremlin announced Wednesday.

Moscow's hypersonic glide vehicle, dubbed Avangard, has been in development for three decades and can travel at least five times the speed of sound, or about one mile per second.

The weapon, which the U.S. is currently unable to defend against, is designed to sit atop an intercontinental ballistic missile. Once launched, it uses aerodynamic forces to sail on top of the atmosphere.

Sources familiar with U.S. intelligence reports assess that the Russian hypersonic glide vehicles are equipped with onboard countermeasures that are able to defeat even the most advanced missile-defense systems. The weapons are also highly maneuverable and, therefore, unpredictable, which makes them difficult to track.

What's more, in May, CNBC learned that Russia successfully tested the weapon twice in 2016, according to sources with direct knowledge of a U.S. intelligence report. The third known test of the device was carried out in October 2017 and resulted in a failure when the platform crashed seconds before striking its target.