Putin arrived in Mariupol by helicopter and then drove himself around the city’s “memorial sites,” concert hall and coastline, Russian news reports said.
Russian airstrikes targeting civilians across Ukraine have left many dead and injured, in retaliation for the destruction of a key bridge linking Russia and Crimea.
Ukrainian officials have repeatedly threatened to strike the bridge and some lauded the attack, but Kyiv stopped short of claiming responsibility.
The Crimean Peninsula holds huge strategic and symbolic significance for both sides.
Ukrainian President Volodymyr Zelenskyy said the Russians have begun their offensive to take control of eastern Ukraine, and it could be a seismic battle.
Former Secretary of State Madeleine Albright discussed the world and the current state of affairs on 'Face The Nation' Sunday, saying "the world is a mess."
Heavy fighting shut down a major steel plant in the southern city, which would be a big prize for Russian forces.
Russia was ousted from the multinational group in 2014 after annexing Crimea. Trump did not mention Crimea or Russia's aggression in Ukraine in his remarks.
Ukraine has voted to impose martial law following the incident, which marks a serious escalation in tensions between the two countries.
Law enforcement initially suspected that the blast was caused by a gas canister blowing up.