President Nixon stuns Americans by announcing U.S. and South Vietnamese incursion into Cambodia "...not for the purpose of expanding the war into Cambodia but for the purpose of ending the war in Vietnam and winning the just peace we desire." The announcement generates a tidal wave of protest by politicians, the press, students, professors, clergy members, business leaders, and many average Americans against Nixon and the Vietnam War.

The incursion is in response to continuing Communist gains against Lon Nol's forces and is also intended to weaken overall NVA military strength as a prelude to U.S. departure from Vietnam.