KYIV, Ukraine — Ukraine and Russia on Thursday vowed fresh assaults in their over-four-year war after Moscow launched a massive barrage on Kyiv, killing at least 27 people, tearing open apartment buildings and sending tens of thousands to shelters. Ukrainian President Volodymyr Zelenskyy said his forces would "definitely" retaliate for the overnight pummelling as he inspected an apartment block that was partially destroyed. The European Union's top diplomat proposed new sanctions on Moscow, as Zelenskyy pressed the United States for licences to manufacture Patriot air-defence missiles. U.N. chief Secretary-General Antonio Guterres condemned Russia's barrage and repeated a ceasefire call. "Attacks against civilians and civilian infrastructure wherever they occur are a clear violation of international humanitarian law and must stop immediately," said his spokesman Stephane Dujarric. But the Kremlin vowed to further ramp up "pressure" on Kyiv, sticking to its no-compromise rhetoric. 'Most massive attack' Russia has routinely launched waves of missiles and drones during its invasion, Europe's