After spending almost two decades in the U.S. military prison at Guantánamo Bay, Cuba, the alleged mastermind of the 9/11 terror attacks, Khalid Shaikh Mohammed, and two of his accomplices have agreed to plead guilty in exchange for sentences of up to life in prison rather than face a death-penalty trial. The settlement agreements with the Pentagon, announced Wednesday, bring partial closure to a case that has dragged on for twenty years and become mired in legal gridlock. Many family...