It's 7 a.m. in Kyiv. Here's what you need to know

As Russian President Vladimir Putin proclaimed the effort to capture Mariupol from Ukraine a "success" and ordered his forces to halt outside the city's besieged Azovstal steel factory, US President Joe Biden said Thursday it was “questionable” whether the city had fallen. Meanwhile, an estimated tens of thousands of civilians in Mariupol remain trapped by air and ground attacks with little opportunity to evacuate safely, and satellite images point to evidence of mass graves outside the city.

Here are the latest developments on Russia's war in Ukraine:  

• Siege of Mariupol a "terrorist operation," Zelensky says: Ukrainian President Volodymyr Zelensky said Thursday that "thousands" of civilians remain blockaded inside Mariupol as he likened the Russian siege to a "terrorist operation." Ukrainian officials on Tuesday also identified the location of apparent mass graves outside the city, claims bolstered by the publication of satellite images collected and analyzed by Maxar Technologies.
• Mariupol evacuations are moving slowly, deputy PM says: The evacuation of civilians is going “very slowly," according to Ukraine's deputy prime minister, amid intense attacks from Russian forces. "On the Russian side, everything is very complicated, chaotic, slow and, of course, dishonest,” Iryna Vereshchuk said on Telegram. Ukrainian commanders on the ground have said Russian forces have not honored agreements to open evacuation corridors or enforce ceasefires.
• Ukraine alleges Russian orders were given to kill POWs: Ukraine’s military intelligence on Wednesday released a purported communications intercept of Russian armed forces referring to an alleged order to kill Ukrainian prisoners of war in the city of Popasna in the eastern region of Luhansk, which is bearing the brunt of Russia’s renewed attack. It appears to feature Russian soldiers saying: “Keep the most senior among them, and let the rest go forever. Let them go forever, damn it, so that no one will ever see them again, including relatives.”
• Neighboring nations say Russia committed genocide: The Estonian and Latvian parliaments adopted statements on Thursday saying Russia has committed genocide in Ukraine, citing mass graves and atrocities discovered in areas since vacated by Russian forces.
• Annexations will cripple Russia, Zelensky says: Zelensky warned Russia on Thursday that any attempts at annexation — similar to Crimea or the so-called breakaway republics in the nation's east — will lead to sanctions that will leave Russia as poor as it was after its civil war in 1917. “I want to say straight away: any ‘Kherson People's Republics’ are not going to fly," he said.
• US sends more aid to Ukraine: Saying there was a "critical window" as Russian forces build up in the east of Ukraine, Biden announced an additional $800 million in military assistance to Ukraine. The new package would include heavy artillery and drones, he said Thursday, along with ammunition.