I should have written "nobody is going to give it (Putin's ABM system) a live-fire test with an ICBM".I'm not so sure about that. The Ukrainians seem to have some daring pilots.
Just like during WW2 you had a bunch of air defense around Berlin but you still found many Allied willing pilots to go on air raids.
Can a Mig-29 (or whatever they fly) reach Moscow undetected and fire a few missile into Vlad's office?
Regardless of the effectiveness of Russian antiaircraft systems, I rather doubt that Putin is above ground very much while he's in Moscow.
There are probably some Ukrainian pilots who would "go Downtown" into Moscow on a one-way trip with or without missiles; just like there probably some Israeli pilots who would drive their planes right into the tunnel entrance of Iran's enrichment facility.