Ukrainian President Volodymyr Zelensky has accused Russia of trying to humiliate the United Nations by raining missiles on Kyiv during a visit to the city by the UN chief, a deadly attack that shattered weeks of relative calm in the capital.

“The Ukrainian forces fought to hold off Russian attempts to advance in the south and east,” Zelensky reported. The UN-backed efforts to arrange safe passage for residents trapped in the ruins of Mariupol continued.

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Several previous attempts to evacuate civilians have fallen through.

On Thursday, Russia pounded targets all over Ukraine, destroying a residential high-rise and another building in Kyiv just as life seemed to be getting a little closer to normal.

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The US-funded broadcaster Radio Free Europe/Radio Liberty said one of its journalists was killed.

Meanwhile, a former US Marine was killed while fighting alongside Ukrainian forces, relatives said in what would be the war’s first known death of an American in combat.

The US has not confirmed the report.

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At least two other foreigners fighting on the Ukrainian side, one from Britain and the other from Denmark, have also been killed.

In an apparent reference to the attack in Kyiv, Russia’s military said it had destroyed “production buildings” at the Artem defence factory.

The bombardment came barely an hour after the Ukrainian President held a news conference with UN Secretary-General António Guterres, who toured some of the destruction in and around Kyiv and condemned attacks on civilians.

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“This says a lot about Russia’s true attitude toward global institutions, about attempts of the Russian leadership to humiliate the UN and everything the organisation represents,” Zelensky said late on Thursday in his nightly video address to the nation.

Kyiv Mayor Vitali Klitschko said the attack was Russian President Vladimir Putin’s way of giving “his middle finger” to Guterres.

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The strikes were the boldest Russian attack on the capital since Moscow’s forces retreated weeks ago following their failure to take the city.