Why Russia Hasn’t Defeated Ukraine

After invading, Russia’s military was expected to sweep through Ukraine within a few days, quickly seizing the capital, Kyiv, and installing a pro-Moscow government. It hasn’t worked out that way. Now, with Russia’s advance stalling, there are signs that President Vladimir V. Putin is ready to wage a much darker, grimmer campaign. Guest: Eric Schmitt, a senior writer covering terrorism and national security for The New York Times.