Russia is still fighting for complete control of the eastern Ukrainian region of Luhansk.
Its troops and artillery have failed so far to dislodge the Ukrainian defenders, who are holding on to the last stronghold in the besieged city of Severodonetsk.
The governor of Luhansk says Russian forces are pushing into nearby areas and bombarding Lysychansk, a city that sits across a river from Severodonetsk.
Meanwhile, Moscow says it retaliated after several Russian-controlled oil and gas facilities in the Black Sea were attacked.
Russia's defense ministry says it launched missiles at a Ukrainian airfield in the region of Odesa and destroyed a hangar that was housing drones.
Russian President Vladimir Putin was at the Kremlin on Tuesday as the battles raged on. He attended a graduation ceremony for future defense and intelligence officials.
Putin said, "Do not forget that the effective use of theoretical knowledge you got when training is only possible after receiving some practical experience."
The president also revealed during the ceremony that Russia is gearing up to deploy state-of-the-art military hardware. He said new ICBMs and surface-to-air missile systems will be used by the end of the year.
On Tuesday, US Attorney General Merrick Garland became one of the latest high-ranking Western officials to visit Ukraine amid the ongoing hostilities.
Garland met with his Ukrainian counterpart, Prosecutor General Iryna Venedictova.
The attorney general said, "The United States is sending an unmistakable message. There is no place to hide. We and our partners will pursue every avenue available to make sure that those who are responsible for these atrocities are held accountable."
Garland said the US has set up a special team to support Ukraine, as it collects and analyzes evidence of war crimes committed by Russian troops.