So far, 2019 is definitely not the best year for arms control, with the INF Treaty dead, the New START treaty extension in limbo and the Open Skies Treaty under increasing pressure.

However, a glimmer of hope appeared late last month when Russia’s Defense Ministry showed its new Avangard hypersonic missile system to U.S. inspectors under the provisions of the New START treaty.

Avangard — reportedly labeled the SS-19 Mod 4 by the U.S. — is one of Russia’s newest and most advanced weapons systems. President Vladimir Putin first announced its development in a March 2018 speech — along with a slew of other new weapons.

The system consists of a hypersonic glide vehicle that is launched by an intercontinental ballistic missile (ICBM) as a booster, though it flies on a trajectory that hardly resembles a ballistic missile and is capable of maneuvering through the atmosphere to bypass missile defense assets and strike enemy targets.

Its actual capabilities remain a topic for discussion, but to dispel widespread confusion, one fact must be emphasized: Traditional ICBM reentry vehicles have much higher terminal speeds than any hypersonic glider as the latter inevitably loses speed when making turns and flying through the atmosphere.

In any case, the Avangard is a real and capable system — even if it will have little immediate impact, since Russia (and the U.S. for that matter), possesses traditional nuclear delivery vehicles that are capable of destroying the enemy without any missile defense-related concerns.

In recent arms control negotiations over the New START treaty, U.S. officials had quite openly requested for Moscow to include all of its newest weapons as one of the conditions for the treaty’s extension. However, their full inclusion seems impossible from a purely technical point of view — there are no definitions in the treaty that would apply to Russia’s new Poseidon nuclear-powered unmanned underwater vehicle, the Burevestnik nuclear-powered unlimited-range cruise missile or the Kinzhal hypersonic aeroballistic missile. Opening up and re-negotiating the treaty before February 2021 also seems unlikely.