Officials in Kyiv have said a "significant portion" of the Russian army is starting a long-anticipated offensive in eastern Ukraine.
US military affairs analyst joins Ukrainian international legion
Malcolm Nance, a well-known US media commentator on military affairs announced on MSNBC that he has "joined the international legion here in Ukraine."
Nance was an officer in the US Navy from 1980 to 2001 and specialized in cryptography and counterterrorism. He is one of the most high-profile Americans to join the fight in Ukraine.
Both the Russian and Ukrainian sides of the conflict have made use of foreign fighters, with Russia bringing in Chechens and Syrians and Ukraine drawing thousands of fighters largely from Western countries.
Biden to discuss Ukraine with US partners
US President Joe Biden will convene a meeting of US allies on Tuesday to discuss the war in Ukraine after Kyiv announced Russia had launched a major new offensive in the eastern Donbas region.
"The president will convene a secure video call with allies and partners to discuss our continued support for Ukraine and efforts to hold Russia accountable as part of our close coordination," the White House said in a statement.
Ukrainian President Volodymyr Zelenskyy said that Russian troops have started a long-anticipated offensive in eastern Ukraine.
"We can now confirm that Russian troops have begun the battle for the Donbas, which they have been preparing for a long time," Zelenskyy said.
Zelenskyy added that a "significant portion of the Russian army is now concentrated on this offensive."
There has been no comment thus far from Russia's Defense Ministry on the latest fighting.
The general staff of the Ukrainian armed forces said Tuesday that Russian forces were attempting to take full control of the eastern Donbas region.
"The occupiers made an attempt to break through our defenses along nearly the entire frontline in the Donetsk, Luhansk and Kharkiv regions," a statement said.
On Monday evening, Ukrainian National Security Council secretary Oleksiy Danilov said that Russian forces had taken over the Luhansk town of Kreminna and one other town, but elsewhere the Ukrainian military was holding out its defense.
Ukraine has been anticipating a renewed Russian assault on Donbas since Russian forces began to pull back from central regions of Ukraine, including towns around the capital Kyiv, in late March.
"The second wave of the war has started," Ukraine's presidential chief of staff Andriy Yermak said Monday in reference to the Russian offensive.
Russia has also continued trying to capture the southeastern port city of Mariupol, which has been under siege since the beginning of the invasion. Control of Mariupol is crucial for Russia as it attempts to secure the Azov coast and create a corridor between Crimea and Donbas.
Summary of Monday's events in Russia's war on Ukraine
The mayor of the besieged city of Mariupol said Russian troops had been "forcibly deporting" civilians from Mariupol to Russia or Russian-controlled regions in Ukraine.
Several weapon shipments have reached Ukraine since the US unveiled a new $800-million (€742 million) package of military aid last week, a senior Pentagon official said. "There have been four flights from the United States arriving into the theater just yesterday" with a fifth flight due shortly, according to the official cited by the AFP news agency.
France's President Emmanuel Macron said he had not spoken to Vladimir Putin after mass killings of Ukrainian civilians in Bucha and in other towns were reported in early April.
Vladimir Putin honored the unit that allegedly committed atrocities in Bucha for the "mass heroism and valor, tenacity and courage." He gave the 64th motorized rifle brigade the honorary title of "Guards." The brigade was allegedly deployed in the town when civilians were executed.
Russia's defense ministry also confirmed a strike on Lviv in western Ukraine, saying they have targeted a military logistic center.
More than 4.9 million citizens of Ukraine have fled the country following Russia's invasion, the UN's refugee agency (UNHCR) said.