From Nicholas Eberstadt for The American, here:
But what, exactly, is this “gorgeous” and “beautiful” (Hu’s words) tune that so entranced China’s visiting leadership?
“My Motherland” is not a “Chinese song” in any ordinary meaning of the term. Instead, it is a Mao-era propaganda classic: the theme from "Triangle Hill" (Shangganling), a film in which heroic Chinese forces fight, kill, and eventually beat Americans in pitched battle during the Korean War.
“My Motherland” epitomizes the “Resist America, Aid [North] Korea” campaign that Beijing embraced during and after the Korean War. It celebrates Sino-American enmity.