Russia escalated its attacks on Kyiv, launching waves of drones and missiles in its first combined aerial assault on the capital in more than 70 days, authorities said.
The attacks came as Washington and Seoul echoed warnings from Ukraine that North Korean troops had begun "engaging in combat operations" alongside Russian forces on the border between the warring countries.
Ukraine's air force said its units had downed four missiles and 37 drones launched by Russia over eight regions of Ukraine overnight and into this morning.
"It is important that our forces have the means to defend the country from Russian terror," President Volodymyr Zelensky said in response to the attack.
Ukraine has for months been appealing to its Western allies to provide more air-defence systems to fend off Russian attacks on cities and critical infrastructure.
The large-scale bombardment comes at a critical moment on the battlefield.
Russian forces are advancing in the east and concerns are growing over future aid for Ukraine after Donald Trump's victory in US presidential elections.
AFP journalists heard explosions ring out over Kyiv and saw dozens of residents seeking shelter in an underground metro station in the centre of the capital.
Kyiv officials said one man was wounded by falling debris from a downed drone in the suburb of Brovary, while emergency services distributed images of firefighters battling flames at one impact site.
A separate drone attack in the Ukrainian-controlled southern region of Kherson, which the Kremlin claims is part of Russia, killed a 52-year-old woman, the regional head said.
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Multiple air raid sirens rang out as authorities said missiles were closing in on Kyiv, which was home to nearly three million people before Russia invaded in February 2022.
"As missiles were approaching Kyiv, the enemy simultaneously launched a ballistic missile attack on the capital. The enemy attack ended with another drone strike," city authorities said.
The attack is the latest in an uptick in escalating strikes on Ukrainian cities, mainly in the south of the war-battered country.
A Russian strike this week on Kryvyi Rig, Mr Zelensky's hometown, killed a 32-year-old mother and her three children.
The Kremlin has repeatedly denied its forces target civilians in Ukraine, a claim its spokesman repeated in response to a question over whether Russian forces were working to minimise civilian casualties.
Over the weekend, Moscow and Kyiv launched record overnight drone attacks on each other.
Ukrainian Foreign Minister Andrii Sybiha said he was "cautiously optimistic" after discussing with US Secretary of State Antony Blinken the possibility of conducting deep strikes on Russia as well as Euro-Atlantic integration.
Kyiv has long been lobbying for Western allies to allow long-range attacks on military targets inside Russia, while also pressing for an invitation to join the NATO alliance.
Allies including the US have been unwilling to permit long-range attacks for fear of further escalating the conflict, and some are opposed to inviting Ukraine to join NATO.
"We discussed issues of long-range strikes and Euro-Atlantic integration. And here we also are cautiously optimistic," Mr Sybiha said in televised comments.
His talks with Mr Blinken in Brussels come at a turbulent time, just one week after Donald Trump won the US presidential election.
Mr Trump has long criticised the scale of US financial and military aid to Ukraine and has vowed to end the war quickly, without explaining how.
Ukraine and its European allies fear this would mean accepting peace on Russia's terms, which would entail large territorial losses and rule out Ukraine ever joining NATO.
The outgoing Biden administration has pledged to promptly deliver what remains of the promised aid packages before Mr Trump's return to the White House in January.
Mr Sybiha said his talks in Brussels had also touched on military aid.
"We have a clear picture - a clear timeframe, clear volumes – of what will be delivered to Ukraine by the end of the year. This helps us strategically to plan our actions on the battlefield," he said.
The assistance, he added, would include weapons and funds for arms production deals.
South Korea's spy agency said North Korean soldiers were "engaging in combat" in Kursk after US officials confirmed Pyongyang's troops were actively fighting for Moscow against Ukraine.
Mr Blinken said earlier he had discussed North Korea's actions with NATO chief Mark Rutte, saying Pyongyang's troops had been "injected into the battle, and now, quite literally, in combat."
That development "demands, and will get, a firm response," he pledged.
Kyiv has warned that Russia has amassed a force of 50,000 troops, including North Korean soldiers, to push out Ukrainian forces from the Russian border region of Kursk.
At the same time, Russian ground forces have been making rapid advances in Ukraine's eastern Donetsk region, which the Kremlin claims is part of Russia.
The Russian defence ministry said its troops had wrested control of the village of Rivnopil, where an estimated 98 people lived before the invasion.
To face both the North Korean threat and the continued Russian assaults, Ukraine has been advocating for allies to allow it to use long-range weapons deep inside Russian territory.
Moscow repeated warnings against the move.
"The response to the use of Western long-range systems on the territory of our country would be inevitable and devastating," said Foreign Ministry spokeswoman Maria Zakharova.
Separately, a source in the Security Service of Ukraine said the agency had orchestrated a car bomb attack in Crimea - the Ukrainian peninsula annexed by Russia in 2014 - that killed senior Russian naval officer Valery Trankovsky.
