Ukrainian President Volodymyr Zelensky said that war means mobilization rules cannot be changed, Reuters reported, quoted by BTA.
He added that if the soldiers were allowed to return home en masse, then Russian President Vladimir Putin "would kill us all."
The Ukrainian leader expressed this opinion to Italian journalist Cecilia Sala, who was released from an Iranian prison earlier this month.
In the interview, Zelensky said that the number of victims suffered by Ukrainians in the war underscored the need to quickly end this conflict.
Ukraine's parliament approved new mobilization rules last year to increase the number of soldiers at the front, but Ukrainian forces remain significantly outnumbered by their Russian adversary, Reuters reported.
"The wartime situation requires the mobilization of people and all the resources we have in the country. Absolutely everyone," Zelensky said in the interview, excerpts of which were posted on the president's Telegram channel.
"And unfortunately, this is the challenge of this war, and that is why we must speed things up to the maximum in order to end this conflict, to force Russia to end this war," Zelensky said.
"Today we are defending ourselves. If tomorrow, for example, half of the army goes home, we really have to surrender on the first day. That's how things are. "If half the army goes home, Putin will kill us all," Zelensky said.
The legislation, approved last year, lowered the conscription age for Ukrainian men from 27 to 25, limited exemptions and imposed fines on those who try to avoid conscription.
But Zelensky and other Ukrainian leaders have rejected the U.S. idea of lowering the conscription age even further.
Russian forces now occupy about 20 percent of Ukrainian territory, Reuters recalls.