Ukraine's defence minister reiterated the view that a new Russian offensive is expected later this month.
At a news conference, Oleksiy Reznikov said not all Western weaponry will have arrived by then, but Ukraine had reserves to hold off Russian forces.
He added that Ukraine had negotiated the supply of new long-range missiles.
It comes as President Volodymyr Zelensky said his troops are facing heavy fighting in Bakhmut, Vuhledar and Lyman in Ukraine's east.
Mr Reznikov said Russia's 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 is expected to prioritise taking the whole of the eastern Donbas as well as launching offensives in the south and east of Ukraine to create a land corridor across all the areas it currently occupies.
The defence minister also confirmed that troops will start training on German-made Leopard tanks from Monday.
Mr Reznikov said Ukraine's new long-range missiles will have 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 in the country's east.
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: "During the 346 days of this war, I often had to say that the situation at the front was tough. And that the situation is getting tougher.
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:
- In the north-eastern city of Kharkiv, five people were wounded after strikes hit civilian buildings in the city, local authorities have said.
- Five others were injured in the Donetsk region during rocket attacks, according to regional leader Pavlo Kyrylenko
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