Russian forces are stepping up their offensive on key cities in eastern Ukraine, but have withdrawn their vessels more than 100 kilometers from Black Sea coasts.
Ukrainian President Volodymyr Zelenskyy said at a news conference in Kyiv on Monday that fierce street fighting continues in Severodonetsk in the eastern region of Luhansk, but that Ukrainian troops will not give up the city.
Zelenskyy said severe battles are taking place in Lysychansk, which faces Severodonetsk on the opposite bank of the Siverskyi Donetsk River, and Slovyansk in the neighboring Donetsk region.
The region's governor, Pavlo Kyrylenko, said on Tuesday that fewer than 24,000 residents remain in Slovyansk. That means nearly 80 percent of the city's 110,000 residents have evacuated.
Ukraine's navy said on Monday that it had pushed Russian warships of the Black Sea Fleet more than 100 kilometers away from Ukraine's coast along the sea.
The Institute for the Study of War, a US think tank, says Ukrainian naval pressure and anti-ship missiles provided by Britain and other countries forced the Russian warships to retreat.
The institute says Ukraine will likely try to leverage the success to alleviate the economic pressure of Russia's blockade on Ukraine's ports.
Russia's navy has conducted missile attacks against land targets from warships deployed off Ukraine.
Russian warships have also blocked navigation by commercial vessels, disrupting Ukraine's grain exports.
Russia's military has taken control of the strategically important Snake Island in the Black Sea. Ukrainian forces have carried out drone attacks to try to recapture the island.