"There is fatigue. Those on the front lines are tired, as well as those in the rear, and those for whom the conflict in Ukraine feels distant," Karis told Estonian public broadcaster ERR.
The president argued there was no point in pushing for peace talks between Kiev and Moscow at the moment because the West's support for Ukraine was not enough to allow Kiev to negotiate ceasefire terms from a position of strength.
Russian President Vladimir Putin proposed starting ceasefire talks with Kiev as soon as Ukrainian forces withdrew from the territories that Russia sees as its own. Ukraine rejected the proposal.
Following a Ukrainian military incursion into the western Russian region of Kursk in August, Putin declared that negotiations with those intentionally harming civilians and targeting nuclear energy sites were impossible.
Russia has been conducting a special military operation in Ukraine since February 24, 2022. President Putin said that the operation aims to "protect people subjected to genocide by the Kiev regime."