Which common game piece did the United States compare Vietnam to?

Domino game pieces

Explanation:

The United States used the term Domino Effect to explain the situation in Asia during the 1960s. The theory asserted the situation of letting a communist nation to takeovers other neighbouring states and converting it under communism. According to the Domino theory, if Vietnam becomes a communist country that would lead countries like Laos, Cambodia, Thailand, India, Japan, the Philippines, and Indonesia to fall under the communism.