How did U. S. foreign policy in Vietnam during the Cold War conflict with traditional
American political ideals?

The Vietnam War had a profound effect on America. The war also drastically decreased Americans' trust in political leaders. In foreign policy, the U.S. suffered from the so-called Vietnam Syndrome: a fear of getting involved in foreign ground wars that might become long, bloody stalemates with no foreseeable end.

they believed democracy was worth the fight

probally   a few days after there called