Russian forces continuing their offensive in Ukraine appear to be shifting focus away from the battleground city of Bakhmut in the eastern region of Donetsk. But observers say Russian losses are mounting.

A Ukrainian army commander said in a post on social media on Tuesday that Russian forces have not given up surrounding and taking control of Bakhmut.

The commander stressed that his troops are determined to protect the city.

Russian forces appear to have shifted their operational focus to the town of Avdiivka, about 50 kilometers south of Bakhmut, and other areas.

Britain's defense ministry said on Tuesday that in recent days Russia has continued to prioritize an operation to encircle Avdiivka, but that its forces have made only marginal progress.

The ministry noted poor discipline and morale among Russian troops, and suggested they have suffered heavy losses in armored vehicles.

Meanwhile, Russian Prime Minister Mikhail Mishustin revealed on Monday that President Vladimir Putin and Belarusian President Alexander Lukashenko will meet on April 6 for talks to boost their countries' bilateral partnership.

The leaders will reportedly meet in Moscow, and could discuss deployment of tactical nuclear weapons in Belarus, which Putin announced earlier.

The Belarusian foreign ministry issued a statement on Tuesday saying the country decided to host Russian tactical nuclear weapons to strengthen its own security and defense capabilities.

It said the decision does not violate the nuclear non-proliferation treaty.