The people of Belgorod have experienced Ukrainian cross-border attacks before, but Saturday's was the deadliest on Russian soil since the start of the war.
Twenty-five people were killed and more than 100 others hurt in the biggest Russian city in close proximity to Ukraine.
The Ukrainian missile strikes came a day after Russia launched its biggest aerial bombardment of the war so far, leaving more than 40 dead.
President Volodymyr Zelensky said this week that Russia had launched 500 missiles and drones against Ukraine in just five days.
Ukraine's response in targeting Belgorod would not go unpunished, vowed President Vladimir Putin. But the city's residents accuse authorities of not doing enough to keep people safe.