Speaking at the “Ukraine. Year 2024” forum in Kyiv, Zelensky said that “each of these losses is a great sacrifice” for Ukraine.

He added that “tens of thousands of civilians” had been killed in occupied areas of Ukraine, but said that no exact figures would be available until the war was over.

It’s the first time that Kyiv has confirmed the number of its losses since the start of Russia’s full-scale war against Ukraine on February 24, 2022.

Russia has also provided few official casualty figures. Independent Russian news outlet Mediazona reported on Saturday that about 75,000 Russian men died in 2022 and 2023 fighting in the war.

A United States intelligence report declassified in mid-December 2023 estimated that 315,000 Russian troops had been killed or wounded in Ukraine. If accurate, the figure would represent 87 percent of the roughly 360,000 troops Russia had before the war, according to the report.

It has been two years since Russia invaded Ukraine and commemorations to mark the second anniversary brought expressions of continued support, new bilateral security agreements and new aid commitments from Ukraine’s Western allies.

But Ukraine’s Defence Minister Rustem Umerov highlighted that they still needed to deliver on their commitments if Kyiv is to have any chance of holding out against Moscow and stressed that delays in arms shipments will cost lives.

“We look to the enemy: Their economy is almost $2 trillion, they use up to 15 percent official and nonofficial budget [funds] for the war, which constitutes over $100bn annually. So basically whenever a commitment doesn’t come on time, we lose people, we lose territory,” he stated, speaking at the Kyiv forum.

Europe has admitted it will fall far short of a plan to deliver more than one million artillery shells to Ukraine by March, instead hoping to complete the shipments by the end of the year.

Umerov highlighted that such delays put Ukraine at a further disadvantage “in the mathematics of war” against Russia, which the West has said is increasingly building a war economy.

Kyiv has also been weakened by the blocking of a vital $60bn US aid package amid political wrangling in the US Congress.

US President Joe Biden stressed the hold-ups directly contributed to Ukraine being forced to withdraw from Avdiivka.

On Sunday, Ukraine’s Prime Minister Denys Shmyhal stated he was “deeply convinced that the US will not abandon Ukraine in terms of financial, military and armed support”.

In recent weeks, fighting has intensified on parts of the front line. On Sunday, Russian shelling and rocket strikes continued to pummel Ukraine’s south and east.

Russian troops also appeared to be pressing on west of Avdiivka, the strategic city whose capture this month handed Moscow a significant victory.

Zelensky told a news conference on Sunday that Ukraine has a clear plan for a new counteroffensive against Russian forces.

Kyiv’s troops conducted a counteroffensive last year, but were unable to break through prepared defensive lines in the Russian-occupied south and east.

“There is a plan [for a counteroffensive], the plan is clear, I can’t tell you the details,” Zelensky continued.

He added that a major shake-up that saw the head of Ukraine’s military replaced earlier this month was connected to the new plan of action on the battlefield.

“This plan is related to the change of management; there are corresponding changes. Several plans will be prepared due to a leak of information.”

Earlier he said that Kyiv’s plans to conduct a counteroffensive last year had been leaked and ended up “on a desk in the Kremlin” before the operation had even begun.

Meanwhile at the forum in Kyiv, besides highlighting issues in military deliveries, Umerov insisted that Ukrainian forces were doing “everything that’s possible, and also what’s impossible, to secure a breakthrough” this year.

The defence minister added that a “strong” military strategy is already in place for the coming months, but did not disclose details.