Ukrainians are reporting "extremely tense" situations in their country's east as Russian troops intensify their offensive to capture the Ukrainian stronghold of Bakhmut in the Donetsk region.

Ukrainian President Volodymyr Zelenskyy said Monday in a video statement on Bakhmut, "The situation is getting more and more difficult."

A Ukrainian commander in the area said the Wagner Group, Russia's private military company, is throwing its most trained units into the battle for the stronghold. The commander said they are trying to break through the Ukrainian defenses to surround Bakhmut.

The US-based Institute for the Study of War also suggests that Russia is accelerating its attacks on Bakhmut. The ISW reports Russian sources claimed that Wagner forces made territorial gains north of Bakhmut.

Ukraine's military intelligence service on Monday expressed a view that Russia is running short of its missiles. The representative says Russia still has thousands of missiles but they use many more of them than they produce.

He says Russia is only capable of manufacturing 30 to 40 missiles per month.

He also pointed out the possibility that Russia will shift its military strategy to cover the missile shortage.