On 14 February, President John F. Kennedy said that U.S. military advisers in Vietnam would fire if fired upon.
Citation:
Richert, Lucas Paul. "President Kennedy declares U.S. advisors in Vietnam will defend themselves".
The Literary Encyclopedia. First published 01 November 2008
[http://www.litencyc.com/php/stopics.php?rec=true&UID=5655, accessed 23 May 2013.]