Pakistan, June 6 -- Former U.S. President Donald Trump's effusive praise of his "very good phone call" with Chinese President Xi Jinping may appear, at first glance, to signal a diplomatic thaw. But in the theatre of global power politics, where every gesture is weighed and every word parsed, the significance of such a call lies not in what was said, but in what it attempts to conceal.

For all the pageantry around Trump's remarks that trade negotiations were "positive," that both sides were in sync on rare-earth exports, and that invitations were exchanged, the call is best understood as a highly orchestrated performance amid a far deeper contest. Much more than tariffs or fleeting goodwill, U.S.-China relations today are about two rival...