Putin gambled on Western hesitation, and now a war born of miscalculation grinds on because neither Moscow nor NATO is willing—or able—to force a decisive end. Why did the war in Ukraine start in 2021?As in 2008 and 2012, but unlike 2017 to 2021, Vladimir Putin sensed an American president would not or could not deter him, so he invaded a former Soviet republic. Under past presidents, Putin saw no downside to grabbing Ossetia, the Donbas, and Crimea. Putin was also led to believe the West or Joe Biden would not challenge him following the recent humiliating U.S. withdrawal from...