Russia's plans to build a hypersonic weapon system that can travel at more than 20 times the speed of sound, and also evade US missile defenses, has predictably rattled the world. Last year, Russian President Vladimir Putin boasted that the Avangard weapons system would be ready by 2019. But some obstacles lie ahead that could impact production, CNBC reported. Specifically, the Kremlin needs to find another source of carbon fiber material to build the Avanguard hypersonic glide vehicles.Russia's current supply of carbon fiber material is unable to withstand the extreme temperatures of hypersonic flight. According to a US intelligence report reviewed by CNBC, Russia is hunting for an alternative source of carbon fiber, but so far has had no luck. "It's expected that they will make no more than 60 of these hypersonic weapons because it's just proving to be too expensive to develop," an anonymous official told CNBC.