Which fear drove four American presidents to send weapons and soldiers to fight in Vietnam? A. fear of drugs pouring into the U. S. from Southeast Asia B. fear of communism spreading to many Asian countries C. fear of a Vietnamese takeover in Asia D. fear of losing valuable markets in Southeast Asia

Four American presidents were driven to send weapons and soldier to fight in Vietnam due to the B. fear of communism spreading to many Asian countries. Around this time, US policymakers relied upon a concept of the "Domino Theory," which argued that if one nation were to fall to communism, countries nearby would then become communist.