President John F. Kennedy authorizes U.S. military advisors in Vietnam to return fire if fired upon. At a news conference, he said, "The training missions we have [in South Vietnam] have been instructed that if they are fired upon, they are of course to fire back, but we have not sent combat troops in [the] generally understood sense of the word." In effect, Kennedy was acknowledging that U.S. forces were involved in the fighting, but he wished to downplay any appearance of increased American involvement in the war. The next day former Vice President Nixon expressed hopes that President Kennedy would "step up the build-up and under no circumstances curtail it because of possible criticism."