Just before the sun came up on Saturday on the Kerch Strait Bridge, a strategically and symbolically important link between Russia and the Crimean Peninsula, a bomb detonated, creating a giant fireball.But Ukrainian elation about the explosion quickly turned into concern about how Russia would respond. And in the days since, Moscow’s retaliation has been to pound Ukrainian cities with missiles in the most sweeping rocket assault since the start of the war.Guest: Michael Schwirtz, an investigative reporter for The New York Times.Background reading: President Vladimir V. Putin vowed that more strikes would follow if Russian targets were hit again.The hail of missiles also seemed intended to appease the hard-liners in Russia who are furious with the humiliating setbacks on the battlefield.For more information on today’s episode, visit nytimes.com/thedaily. Transcripts of each episode will be made available by the next workday.