Kramatorsk (Ukraine) (AFP) - Ukrainian forces have for months been holding at bay a gruelling Russian offensive in battered towns and heavily shelled trenches spanning the eastern front line.
But now, with the Kremlin's forces running out of steam after making only incremental gains over the winter onslaught, Ukraine is preparing to hit back.
"If our senior military staff say we have enough troops, enough shells -- enough everything -- to attack, then we're ready," a Ukrainian serviceman, who identified himself as Mark, told AFP in the Donetsk region this week.
Russia was beaten back in embarrassing defeats near the capital Kyiv, Kharkiv and Kherson last year but analysts now say Ukraine has a short window to deliver a larger blow.
Recently conscripted Russian forces are badly depleted after their lacklustre offensive, while Kyiv has stockpiled ammunition, taken in long-range artillery and battle tanks from the West and is bolstering its army.
"Who knows when Ukraine will get this chance again," said Mykola Bielieskov, a research fellow at the National Institute for Strategic Studies in Kyiv.
"It's now or never," he told AFP.
- Getting the timing right -
A key question is: when?
The defence ministry recently posted tongue-in-cheek footage of a serviceman dancing in a muddied trench with the caption: "Once the ground hardens, it will be possible to launch an offensive."
"But more important than the weather is for Ukrainian troops to master the weapons it was promised from the West and to synchronise intelligence and logistics," said Bielieskov.
He estimated that Ukraine's offensive preparations may culminate by June or July, much later than other forecasts of later this month or early May.
"Everyone in Kyiv understands that an offensive launched prematurely is less likely to succeed," Bielieskov added.
The southern Zaporizhzhia and Kherson regions -- that the Kremlin claimed to have annexed last September -- are likely targets, and their capture by Kyiv would rupture a land bridge between Russia and the annexed Crimean peninsula.
And when Ukraine does begin its pushback against the fortified Russian positions, artillery and enough shells will be key in a battle dominated by long-range duels.
But Ukrainian servicemen at different frontline sections have complained to AFP that they are outgunned by Russian forces with a seemingly endless supply of shells.
The European Union last month agreed a two-billion-euro ($2.2-billion) plan to keep Ukraine stocked but observers estimate nearly half of that package would need to be delivered for Ukraine's offensive to succeed.
"Unlike Russians, we are not concerned with the quantity of fire, but the precision of fire.That's how Ukraine plans to make up for this deficit," Bielieskov said.
"The only problem is that we are paying for this in people."
And military recruitment ads throughout Kyiv point to large-scale efforts to build up a new force for the offensive after losses from a year of battle.
Kyiv has not disclosed figures but the head of Russia's mercenary group Wagner has cautioned that Moscow should prepare to rebuff a Ukrainian force of between 200,000 and 400,000 troops.
'Difficult issue'
Ukraine is also urging Western allies to equip its armed forces with fighter jets to match Russia in the air.
Leaked US intelligence suggest that Ukrainian stockpiles of missiles for its air defence systems are depleting, giving a potential opening to Russia's notorious air force.
"Without air superiority, carrying out offensives under the fire of enemy aircraft is -- to put it mildly -- a somewhat difficult issue," Ukrainian air force spokesman Yuriy Ignat said recently.
The leaks appear to suggest Ukraine is low on some hardware and precision ammunition.Observers say some details could compromise Ukraine's future offensive but Kyiv has denied that.
"I don't see anything in these files that would have a wow effect," presidential aide Mykhalo Podolyak told local media this week, adding that offensive plans "were still being worked out".
The stakes for Ukraine are high.
"US and European countries can sustain Ukraine's war effort but may not be able to provide a decisive military advantage over Russia for some time after this period," said US-based military analyst Michael Kofman.
Bielieskov said Kyiv needs to disprove Kremlin talking points that the West must accept its gains and prove to allies it can keep clawing back territory.
"Everyone wants to be on the winning side," he said.
A year after Russia invaded, observers say Ukraine has emerged the more motivated force.
"I can only speak for my sector -- six kilometres (four miles) forward and three kilometres on either side," Mark, 42, said on the Donetsk front line.
"We're ready to do what needs to be done."
