Russia will be held responsible for every strike on Ukraine's cities, President Volodymyr Zelensky said in his evening video address on Dec. 30.
"For every Shahed drone, for every Russian missile, there will be a fair responsibility of the terrorist state, both political and very practical," he said.
According to Zelensky, Ukraine is preparing to produce more weapons in 2024.
Russian forces attacked downtown Kharkiv on Dec. 30, injuring 20 people, Kharkiv Mayor Ihor Terekhov reported.
The city was reportedly attacked with at least six missiles, one of which struck a residential building, causing a fire.
The attack comes a day after Russia unleashed the largest air attack on Ukraine.
Russia unleashed its largest attack on Ukraine on Dec. 29, targeting multiple Ukrainian regions, including Odesa, with 158 missiles and drones.
The latest report pushes the total death toll of the Dec. 29 attack to 41 people: 17 in Kyiv, nine in Zaporizhzhia, six in Dnipro, five in Odesa, three in Kharkiv, and one in Lviv. The air attack injured over 160 people.
Casualties were previously reported in Kyiv, Odesa, Dnipro, Lviv, Kharkiv, and Zaporizhzhia.
Zelensky said it was "the most massive attack," while the Air Force called it "the largest air attack."
Ukraine downed 114 of 158 Russian missiles and drones, according to the Air Force. Among the downed targets were 27 Russian Shahed attack drones and 87 cruise missiles.
In total, Russia launched 36 drones, at least 90 Kh-101/Kh-555/Kh-55 cruise missiles, eight Kh-22/Kh-32 cruise missiles, 14 S-300/S-400/Iskander ballistic missiles, as well as five Kinzhal ballistic missiles, four anti-radar missiles, and one Kh-59 cruise missile.
"Russia was fighting with almost everything it has in its arsenal," Zelensky wrote on Telegram in the morning following the attack.
Air Force spokesperson Yurii Ihnat said on air that an attack of this scale "has not been seen for a long time."
Zelensky said the attack destroyed or damaged over 100 private houses, along with 45 multi-story buildings, schools, two churches, hospitals, maternity wards, and numerous commercial and warehouse premises across Ukraine.
"Targets are already familiar for Russia," he said.