"Jan 30, 1968: Tet Offensive shakes Cold War confidence" "Jan 30, 1968: Tet Offensive shakes Cold War confidence" Tet Offensive shakes Cold War confidence "Jan 30, 1968: Tet Offensive shakes Cold War confidence" "Jan 30, 1968: Tet Offensive shakes Cold War confidence" "Jan 30, 1968: Tet Offensive shakes Cold War confidence"