17 Dead in Kyiv — Why Didn't Air Defenses Hold?

Are Ukraine's air defenses running low on interceptors, or being deliberately overwhelmed by sheer volume? Russia's overnight missile and drone barrage killed 17 people in Kyiv and its region in one of the deadliest single-night attacks on the capital in recent memory, with additional deaths in Sumy including two children. Is this a sign Western air-defense supplies aren't keeping pace with the war's intensity, or a one-off saturation attack timed for maximum shock?