"Any concession to the Russian Federation would instantly lead to an escalation of the war. So the war will not stop. It will just be put on pause for some time," he told Reuters in an interview in the heavily guarded presidential office, where some of the windows and corridors are protected by sandbags.
"After a while, with renewed intensity, the Russians will build up their weapons, manpower and work on their mistakes, modernise a little, fire many generals... And they'll start a new offensive, even more bloody and large scale, taking into account all mistakes."
Podolyak dismissed as "very strange" calls in the West for an urgent ceasefire that would involve Russian forces remaining in territory they have occupied in Ukraine's south and east.
Both sides say peace talks have stagnated. Each blames the other.