As mentioned in The Pod Bay Nasa Spaceflight has written: Soyuz 2-1B launches Tundra missile detection spacecraft.
What are Tundra missiles, and why are they so hard to detect that there would have to be a special spacecraft designed and put into orbit to detected them?
The spacecraft's name is Tundra (or EKS). This is a ballistic missile detection system, designed to detect missiles launched from the US, or China (or their submarines, or insert rogue state here) and heading for Russia with their nuclear warheads.
The key to surviving a nuclear attack is early warning. Flight time is only 30 minutes to go halfway across the world, so you want to detect these missiles as early as possible. When the launch site is not visible from your territory, you have to use a satellite to monitor the launch site.
