As the second year of Donald Trump’s presidency and sixth of Xi Jinping’s draws to a close, the world seems to be witnessing one of those epochal clashes that can change the contours of global power. Just as conflicts between American President Woodrow Wilson and British Prime Minister Lloyd George produced a failed peace after World War I, competition between Soviet dictator Joseph Stalin and American President Harry Truman sparked the Cold War, and the rivalry between Soviet leader Nikita Khrushchev and President John F. Kennedy brought the world to the brink of nuclear war, so the empowered presidents of the United States and China are now pursuing bold, intensely personal visions of new global orders that could potentially reshape the trajectory of the 21st century—or bring it all down.