Russia is preparing to launch a fresh assault in eastern Ukraine to try to take the city of Kharkiv and encircle the country’s heavily fortified eastern front line, Ukraine’s defense ministry said on Monday.
Separately, U.S. President Joe Biden's national security adviser Jake Sullivan also said Russia probably plans to deploy tens of thousands of soldiers in eastern Ukraine as it shifts its focus to the country's south and east.
Russia was attacking the towns of Rubizhne and Popasna in the Luhansk region to lay the way for an assault on the regional capital of Severodonetsk and also massing forces to capture the besieged port of Mariupol, Ukraine's defense ministry spokesperson Oleksandr Motuzyanyk said.
Severodonetsk and Mariupol lie at the northernmost and southernmost ends of Ukraine’s several-hundred-kilometer "line of contact," the cease-fire line that Ukrainian forces have held against Russian-backed separatist forces in Donbass since 2015.
"At this juncture we believe Russia is revising its war aims" to focus on "eastern and parts of southern Ukraine rather than target most of the territory," Sullivan told reporters at the White House on Monday.
The goal was likely to "surround and overwhelm" Ukrainian forces in the region, he said. "Russia could then use any tactical success it achieves to propagate a narrative of progress and mask ... prior military failure."
Big attack due in eastern Ukraine
Separately, the governor of the eastern Luhansk region also said the Russian troops were preparing for a big attack in the region, urging a mass evacuation.
"We see that equipment is coming from different directions, they are bringing manpower, they are bringing fuel," Serhiy Gaidai said in a video statement on Telegram.
"We understand that they are preparing for a full-scale big breakthrough," he added. Gaidai urged residents to leave the region as soon as possible. "Please don't wait for your homes to be bombed," he said in a separate video.
"Do not hesitate," he added, specifying that 1,000 people had been evacuated on Monday.
A senior Pentagon official on Monday said Russia has removed about two-thirds of the troops it had around Kyiv – who were mostly sent back to Belarus with plans to redeploy elsewhere in Ukraine.
Motuzyanyk said Russian units were moving out of Belarus and into Russia, and Moscow was readying fuel and ammunition stockpiles in areas bordering east Ukraine.
Russia was also preparing medical facilities for a potential influx of casualties among its troops, he said at a briefing.
Russian President Vladimir Putin's invasion, which began on Feb. 24, is Europe's bloodiest since World War II. Russia calls it a "special military operation" aimed at protecting civilians.
Assistance to Ukraine, sanctions on Russia
Sullivan said the Biden administration would announce fresh military assistance for Ukraine in the coming days. He said further sanctions against Russian energy are on the table in talks with European allies.
Sullivan said the next phase may be protracted with Russian troops outnumbering Ukraine's. Moscow would likely seek to control a far broader swath of eastern Ukraine than separatists controlled prior to the invasion, he said.
In the south, Russia will likely seek to hold the city of Kherson to control the flow of water to Crimea, which it annexed in 2014. He said the Kremlin was expected to launch further air and missile strikes across the rest of the country.
Biden on Monday accused Putin of war crimes and called for a trial, adding to the global outcry over civilian killings in Bucha, a town recaptured by Ukrainian troops as Russian forces regrouped.
Russia categorically denied murdering civilians, including in Bucha. Its U.N. envoy Vassily Nebenzia promised Russia would present "empirical evidence" to the Security Council that its forces had not been killing civilians.