Russian President Vladimir Putin speaks during an annual nationwide televised phone-in show in Moscow, Russia June 20, 2019. Sputnik/Alexey Nikolsky/Kremlin via REUTERS

MOSCOW (Reuters) - Russian President Vladimir Putin said on Thursday that a U.S. military attack on Iran would be a catastrophe for the Middle East that would trigger a surge in violence and a possible refugee exodus.

Putin, speaking during his annual televised question and answer session, said Moscow believed Tehran was in full compliance with its nuclear commitments and called sanctions against Iran groundless.