The terrorist attacks on the United States nearly 20 years ago brought profound change in America and the world. The death and devastation stirred grief, rage and war. It also sparked solidarity, not only in the United States but among its allies — even some rivals. As NATO countries rallied to America’s defense, Russia offered support in ways unthinkable in the Cold War. Iranians mourned American deaths in candlelight vigils. Two decades later, that global goodwill is long gone. Many of the legacies of Sept. 11, 2001, have come undone, partly because of the way the U.S. conducted 9/11 wars in Iraq and Afghanistan.