A billionaire at the center of U.S.-China tensions is waging a mysterious legal battle against two D.C. conservatives over a private espionage deal gone bad. The fight touches on a pair of think tanks, a senator』s widow and the capital』s tight-knit group of China hardliners, adding a new chapter to an international saga that has divided the Trump administration and the president』s external allies. It began when a firm tied to the billionaire, real estate magnate Guo Wengui, allegedly hired ...