Russian forces have continued moving toward eastern Ukraine ahead of a major planned offensive in the Donbas region, while conditions in Mariupol remain dire, with thousands of civilians reported dead and Russian forces inching toward full control of the port city.
Ukrainian commanders and Western officials say Russia has continued to shift its forces from areas north of Kyiv, and from Belarus, toward Kharkiv and the Donetsk and Luhansk regions, where fighting has been ongoing since 2014.
Officials expect Russia to mount a new offensive, possibly with the goal of taking the remaining territories of the Donetsk and Luhansk regions that are still controlled by Ukrainian government forces.
The death toll from the conflict, which erupted when Russia invaded Ukraine on February 24, remains unclear.
Ukrainian commanders said on April 12 that 19,500 Russian troops had been killed to date. The most recent official Russian Defense Ministry tally, in late March, was about 1,370.
U.S. officials say publicly that Russia has lost at least 10,000 troops, and privately, U.S. and Western officials put the figure closer to the Ukrainian estimate -- which would mean Russia has lost more troops in Ukraine than it did in the 10 years of the Soviet war in Afghanistan.
Ukraine has not released its own casualty figures, saying it is a state secret, but President Volodymyr Zelenskiy said publicly in mid-March that about 1,300 Ukrainian soldiers had been killed.
A U.S. Defense Department official said on April 11 that Russian forces were reinforcing around the Donbas region, including near the town of Izyum, which reportedly fell to Russian troops last week.
A Russian convoy including command and control vehicles, and infantry and helicopter support units, was seen heading for Izyum, the official said.
The official also said more than 60 Russian battalion tactical groups -- each numbering between 800 and 1,000 troops -- were believed to have deployed from Kherson in south-central Ukraine, to the northeast through the Donbas, up to the Russian border.
Russia has also appointed a new general to take unified command of the Donbas offensive, a move Western officials said appeared to be aimed at resolving the confusion and missteps that plagued Russian forces in the first phase of the war.
Mariupol, a major port on the Sea of Azov, has been the site of an intense siege by Russian forces for weeks, and the city now resembles an apocalyptic landscape. Russian forces are fighting street-by-street combat with determined Ukrainian marines and the Azov Battalion.
On April 11, Myhaylo Podolyak, a top adviser to Zelenskiy, said in a post on Twitter that Ukrainian forces were "surrounded and blocked" in Mariupol.
Speaking to South Korea's parliament on April 11, Zelenskiy said Russia had "completely destroyed Mariupol and burned it to ashes".
"Tens of thousands of Mariupol citizens must have been killed at least," he said according to a transcript from the president’s office.
Mariupol Mayor Vadym Boychenko was quoted on April 12 as saying that the latest estimate was that around 21,000 civilian residents of Mariupol have been killed since the start of the Russian invasion.
Ukrainian and Western officials also said they were investigating reports that a chemical weapon might have been used against Azov fighters and Ukrainian marines in Mariupol.
A U.S. official speaking on the condition of anonymity was quoted by Reuters on April 12 as saying that the United States did not have information to confirm any movement of chemical agents by Russia in or near Ukraine.
Kharkiv, Ukraine's second-largest city, has also suffered major damage, but remains under Ukrainian control. Oleh Synehubov, the head of the regional administration, said in a post on Telegram on April 11 that eight people were killed by shelling, but Ukrainian forces continued to defend the city.
Peace talks are all but stalled now, as Zelenskiy's government rejects Russian ultimatums, and the Kremlin shifts its attention to the Donbas. European diplomats have sought, unsuccessfully so far, to try to nudge Russian President Vladimir Putin away from continued onslaught.
Speaking on April 12 during a visit to the Vostochny Cosmodrome in eastern Russia, Putin called the war and its military objectives "noble," and he predicted Russian forces would be successful.
"Its goals are absolutely clear and noble," Putin was quoted as saying.
Putin asserted again that Russia was forced to invade Ukraine as a way to ensure Russia's security. Among other arguments, the Kremlin has said Ukraine joining NATO would be a critical threat to Russia. For its part, NATO has said Ukraine might join the alliance someday in the future, but not anytime soon.
The Russian leader also again asserted that Russian forces were helping people in Ukraine; an echo of another Kremlin argument that native Russian-speakers in Ukraine were somehow in danger.
"On the one hand, we are helping and saving people, and on the other, we are simply taking measures to ensure the security of Russia itself," Putin argued. "It's clear that we didn't have a choice. It was the right decision."
Podolyak said peace talks were very hard but they were continuing at the level of working sub-groups. He told Reuters that Russia was trying to put pressure on the talks with its public statements.
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