Russian President Vladimir Putin claimed his troops were victorious in the battle for Mariupol, despite the fact that thousands of Ukrainian troops remain in the giant Azovstal steel mill complex.

Putin ordered his troops not to storm the stronghold but to seal it off “so that not even a fly comes through.”

Russia has ceaselessly bombarded the port city for almost two months and appears to control most of the city. But a few thousand Ukrainian troops, by Moscow’s estimate, have stubbornly held out for weeks at the steel plant.

Ukrainian officials also said about 1,000 civilians are also trapped there. Deputy Prime Minister Iryna Vereshchuk on Friday called for Russia to open up humanitarian corridors for civilians in the plant to evacuate.

U.S. President Joe Biden pushed back on Putin’s claims that Mariupol had fallen to Russia. “It’s questionable whether he does control Mariupol,” Biden said. “There’s no evidence yet that Mariupol has completely fallen.”

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Latest developments:

►Satellite images showed what appeared to be mass graves near Mariupol, and the city’s mayor said Russian troops have buried as many as 9,000 civilians killed in the conflict in a nearby mass grave in order to cover up “military crimes.”

►The U.N.’s human rights office said Friday its investigators had documented at least 50 civilian deaths, including by summary execution, in the Kyiv suburb of Bucha.

►The U.K. plans to reopen its embassy in Kyiv next week, Prime Minister Boris Johnson said Friday.

►In his nightly address Thursday, Ukrainian President Volodymyr Zelenskyy said Russia had rejected a proposal for a truce during the Orthodox Easter holiday.

►U.S. Secretary of Defense Lloyd J. Austin III will travel to Germany next week to meet with a handful of nations to discuss the current and future defense needs of Ukraine, Pentagon Press Secretary John F. Kirby said. 

Russian official: Control of eastern Ukraine will allow ‘influence’ over economy

A Russian military official on Friday laid out wider aims in the country’s new phase of the war in eastern Ukraine, saying Russia was seeking full control of the Donbas and southern Ukraine.

That control “will provide a land corridor to Crimea, as well as influence (over) the vital objects of the Ukrainian economy,” said Rustam Minnekayev, acting commander of Russia’s Central Military District.