Ukraine's outgoing defence minister has said the country is anticipating a new Russian offensive later this month.
At a news conference, Oleksiy Reznikov said not all Western weaponry will have arrived by then, but Ukraine had enough reserves to hold off Russian forces.
President Volodymyr Zelensky said troops were fighting fiercely in Bakhmut, Vuhledar and Lyman.
Mr Reznikov's comments came hours before it was announced that he was to be replaced as defence minister.
Military intelligence chief Kyrylo Budanov will take his place, according to a Ukrainian politician from Mr Zelensky's party.
The shake-up comes amid a series of corruption scandals that has plagued the defence ministry.
Mr Reznikov has denied media reports that some defence officials are suspected of embezzling public funds for the procurement of food for the army.
Ukrainian lawmaker David Arakhamia announced the reshuffle on Sunday, saying that "war dictates personnel policies". Mr Reznikov, a familiar face in Ukraine's efforts to secure Western weapons, will now become minister for strategic industries.
President Zelensky has already fired a number of senior officials as part of a broad anti-corruption drive across his government.
At an earlier news conference, Mr Reznikov said Russia did not have all of its resources ready to launch an offensive, but may do so anyway as a symbolic gesture, given the one-year anniversary of Moscow's full-scale invasion on 24 February.
He said Russia was expected to prioritise taking the whole of the eastern Donbas as well as launching offensives in the south of Ukraine.
Mr Reznikov made similar comments to French TV earlier this month.
The defence minister also confirmed that troops would start training on German-made Leopard tanks from Monday.
Mr Reznikov said Ukraine had secured new long-range missiles with a range of 90-mile (150km), but they will not be used against Russian territory - only against Russian units in occupied areas of Ukraine.
"I am sure that we will win this war," said Mr Reznikov, but he added that without the delivery of Western fighter jets, "it will cost us more lives".
Despite the flow of Western weapons to Ukraine, Russia has made gains around the Bakhmut area in recent days, as Russia's army throws more and more soldiers into combat.
Russia's paramilitary mercenary group Wagner have led much of the fighting in the area.
Its head, Yevgeny Prigozhin, said there are fierce battles for every street in some areas of the city, and Ukraine's armed forces were "fighting to the last".
Russian forces have been attempting to seize control of Bakhmut for months - making it the longest battle since Russia invaded Ukraine almost a year ago.
Taking the area is important to Russia as part of its aim to control the whole of the Donbas region.
It would also signify a turnaround in Russia's fortunes after it lost ground in Ukraine during recent months.
Speaking during his nightly address, President Zelensky said: "Things are very difficult in Donetsk region - fierce battles." But, he added, "we have no alternative to defending ourselves and winning".
The UK's Ministry of Defence said Ukrainian forces in Bakhmut are getting increasingly isolated as the Russians continue to make small advances in its attempt to encircle the town.
It added that the two main roads into Bakhmut were likely being threatened by direct fire.
In other developments: