President Volodymyr Zelenskyy has acknowledged battlefield progress has been "slower than desired", weeks into Ukraine's military offensive to recapture areas occupied by Russia.
"Some people believe this is a Hollywood movie and expect results now. It's not," he told the BBC, Report informs.
"What's at stake is people's lives."
Mr. Zelenskyy said the military push was not going easily because 200,000 sq km (77,220 sq miles) of Ukrainian territory had been mined by Russian forces.
"Whatever some might want, including attempts to pressure us, with all due respect, we will advance on the battlefield the way we deem best," Mr. Zelenskyy added.
He reinforced the need for Ukraine to be given security guarantees from NATO but said ultimately the goal was membership of the defensive alliance.
He made clear that "victories on the battlefield are necessary" and that Ukraine would never sit down, whoever was president in Moscow, if Russia remained on Ukraine's territory: "No matter how far we advance in our counter-offensive, we will not agree to a frozen conflict because that is war, that is a prospectless development for Ukraine."