Sun Tzu, the ancient author of The Art of War, must be throwing a rice wine party in his heavenly tomb in the wake of the shirtsleeves California love-in between President Obama and President Xi Jinping. "Know your enemy" was, it seems, the theme of the meeting. Beijing was very much aware of—and had furiously protested—Washington’s deep plunge into China’s computer networks over the past 15 years via a secretive NSA unit, the Office of Tailored Access Operations (with the apt acronym TAO). Yet Xi merrily allowed Obama to pontificate on hacking and cyber-theft as if China were alone on such a stage.