Both sides claim victory while its regarded as a stalemate. Why is it considered a stalemate and why couldn`t either country have a clear victory over the other.
Why is it considered a stalemate
Because it was status quo ante bellum, no territorial change occurred between the participant of the war. Neither was any regime change happened. Saddam was still there in Iraq as was the Ayatollah still in Iran.
More here, The Iran-Iraq War: New International Perspectives