Ukraine's President Volodymyr Zelensky said 31,000 Ukrainian soldiers had been killed in the war with Russia, in a rare official statement on military losses sustained during the two-year war.
At a press conference in Kyiv, Mr Zelensky said: "31,000 Ukrainian soldiers have died in this war. Not 300,000 or 150,000, or whatever Putin and his lying circle are saying. But each of these losses is a great loss for us."
During the press conference Mr Zelensky also said his country's victory "depends" on support from the Western world and said he was "sure" the US would approve a critical package of military aid.
"Whether Ukraine will lose, whether it will be very difficult for us and whether there will be a large number of casualties depends on you, on our partners, on the Western world," Mr Zelensky said.
He added: "there is hope for Congress, and I am sure that it is going to be positive."
Asked if he would talk to Russian President Vladimir Putin, Mr Zelensky said: "Can you talk to a deaf person? Can you talk to a man who kills his opponents?"
Mr Putin's main opponent Alexei Navalny died in an Arctic prison this month.
"He sees himself (in power) by 2030, we would like to finish with him sooner," Mr Zelensky added, mocking an upcoming presidential election in Russia that is likely to extend Mr Putin's long rule until 2030.
Ukraine planning fresh counteroffensive against Russia
Ukraine has a clear plan for a new counteroffensive against Russian forces, President Volodymyr Zelensky has said, adding that he could not disclose details publicly.
Ukraine'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," Mr Zelensky said.
He added that a major military shakeup 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," Mr Zelensky said, without elaborating.
Mr Zelensky claimed that Ukraine'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.
He did not say how that leak had occurred.
Mr Zelensky also said that troop rotations were critically important for the war effort and that Ukraine needed to better prepare its reserve forces.
The Ukrainian leader predicted that Russian forces will attempt to conduct another offensive in Ukraine in late May or summer.
"We will prepare for their assault. Their assault that began on 8 October has not brought any results, I think," he said.
Half of Western arms delivered late, says Ukraine
Mr Zelensky's comments come as the country's defence minister Rustem Umerov said half of Western military aid to Ukraine is delivered later than promised, delays that hobble Ukraine's ability to defend itself against Russian attacks and cost Ukrainian lives.
Ukraine, which is struggling with an ammunition shortage, has for months said that Western aid is too slow to reach it and that the hold-ups have real consequences as the war against Russia enters its third year.
"At the moment, commitment does not constitute delivery," Mr Umerov said during a forum dedicated to the second anniversary of Russia's invasion.
"50% of commitments are not delivered on time," he added.
Europe has admitted it will fall far short of a plan to deliver more than one million artillery shells to the country by March, instead hoping to complete the shipments by the end of the year.
Mr Umerov said 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.
Mr Umerov said that delayed aid will mean Kyiv will "lose people, lose territories", especially given Russia's "air superiority".
"We do everything possible and impossible but without timely supply it harms us," he said.
Kyiv has in recent weeks been weakened by an ammunition shortage, with a vital $60-billion US aid package blocked by political wrangling in the US Congress.
US President Joe Biden said the hold-ups directly contributed to Ukraine being forced to withdraw from the frontline town of Avdiivka earlier in February, handing Russia its first territorial gain in almost a year.
Ukraine's Prime Minister Denys Shmygal said he was "deeply convinced that the US will not abandon Ukraine in terms of financial, military and armed support."
President Volodymyr Zelensky had pressed G7 leaders to ensure the fast delivery of weapons.
The Ukrainian leader sought to rouse the country's military and political backers on the two year anniversary of Russia's invasion, telling them: "Putin can lose this war" and "we will win".
During a service in the Vatican, Pope Francis called for intensified efforts to find a "just and lasting peace" to the conflict.
"There have been so many victims, so many wounded, so much destruction, so much anguish and so many tears over what has become a terribly long period - the end of which we cannot yet foresee," he said.
"We will win," he said at a ceremony at Kyiv's Gostomel airport, which was targeted by Russia in the first days of the all-out assault in 2022.
