I doubt it means anything. I always assume there are three or four Russian submarines off our coast... I live ten miles from PavPaws... that’s the Air Force facility that tracks submarines in the Pacific.
“one feature of the Zircon hypersonic missiles is the ability to reliably overcome today’s advanced air defence and missile defence systems. The missile’s flight speed exceeds Mach 9, and the range is over 1,000 kilometres.”
Russia, at least a decade ago, began designing superweapons which slip past our defense alerts.
This is one. Mach 9. They say you can’t see it at all, just what happens after it hits.
What is “combat duty” ??? Anyone?
No doubt full of 1970's era tech.