WHY did Russia blow up their own satellite?

Today we learned Russia has conducted an ASAT missile test and destroyed one of its own old satellites. Normally this wouldn’t be much of an issue. Countries test their weapons regularly. Plus it was their own satellite. Under different circumstances this would have be a normal news and we wouldn’t even read the details. Unfortunately, this is news we cannot ignore. The satellite in question was in an orbit of about 400 km. That orbit is very very popular. One, ISS. I mean who doesn’t know at this point. And 2, there are many nanosatellites in that orbit. It is close to earth and you can collect a lot of useful data from that orbit. The debris created by this test will endanger the ISS and god knows how many satellites that are currently in LEO.
Now let’s play the devil’s advocate for a moment. What would be a good reason to destroy that particular satellite? surely , Russia has many other satellites. Perhaps some in the 200 km range. Could it be

  1. They were trying to hide something? Maybe they didn’t want anyone to find out that the satellite was painted in pink paint? ~ Unlikely, the satellite in question was launched in the 1980’s. Nobody cares about such an old satellite. 
  2. They needed the space? Maybe they have a replacement satellite ready? Nope. That can’t be a good reason. The only way to vacate an orbit is to fire the booster and set course for the sea
  3. Maybe it was their test requirement. Maybe the goal of this ASAT was to destroy something at 400 km. could be. But why would they risk their own cosmonauts? Currently there are 2 cosmonauts in ISS right now. This test put their lives in danger too. Even if this was a requirement, where was the courtesy announcement? The the navy conducts live firing exercises, they make sure there are no fishermen at the sea. This is a common practice.

Now I don’t have the president’s Putin’s phone number nor  am I a specialist on global politics. So this is my personal opinion, take it with a grain of salt. If you search for news on Russia right now, you’ll see that there are some tensions related with territory and EU politics. My bet is that this was a show of power. Nothing else. My guess is they didn’t want to launch an ICBM into the sea and gather too much news attention. So they picked space and aimed their missile at their own satellites. This way they can flex their muscle just enough to make everyone notice but not enough to create a global news cycle.
This is the misfortune of the field I chose to work