Russia and Ukraine discussed further prisoner swaps on Wednesday at a brief session of peace talks in Istanbul, but the sides remained far apart on ceasefire terms and a possible meeting of their leaders.

Ukraine and Russia attacked targets on each other's territory on Thursday after brief direct talks between the two sides failed to make any progress on steps to end nearly three-and-a-half years of war.

Both Ukrainian and Russian delegate arrived in Turkey Wednesday ahead of a third round of talks. Ukrainian and Western officials have accused the Kremlin of stalling in the talks in order for its bigger army to capture more Ukrainian land.