(CNN)     Ukraine claims it has evidence Russia fired an advanced hypersonic missile – one that experts say is almost impossible to shoot down – for the first time in the almost 2-year-old war.

The government-run Kyiv Scientific Research Institute of Forensic Expertise said in a Telegram post that debris recovered after a February 7 attack on the Ukrainian capital pointed to the use of a Zircon hypersonic cruise missile by the Russian military.

“Markings on the parts and fragments, the identification of components and parts, and the features of the relevant type of weapon” point to the first-ever use of the Zircon in combat, said the institute, which is part of Ukraine’s Justice Ministry.

Ukrainian authorities reported four people were killed and 38 others injured in Kyiv during the February 7 attacks, but no casualties have been directly attributed to the alleged Zircon missile.

There was also no mention of the launch platform for the missile, though previous reports in Russian state media say it has been deployed on a warship.

Experts say the Zircon, if it lives up to what the Russian government says about it, is a formidable weapon.

Its hypersonic speed makes it invulnerable to even the best Western missile defenses, like the Patriot, according to the United States-based Missile Defense Advocacy Alliance (MDAA).

The alliance says its speed has been put at Mach 8, or almost 9,900 kilometers per hour (6,138 mph). Hypersonic is defined as any speed above Mach 5 (3,836 mph).

“If that information is accurate, the Zircon missile would be the fastest in the world, making it nearly impossible to defend against due to its speed alone,” the alliance says on its website.