"the United States has never before confronted the question of extending unilateral trade preferences to a country that has rejected a reciprocal trade agreement"

Is the quote in the title to this post a threat to Costa Ricans voting tomorrow on approval of CAFTA?  It does sound a bit like one, with the suggestion that if CAFTA is not approved, unilateral trade preferences to Costa Rica might not be renewed.  Is such a threat likely to have the desired effect?  Would it really be followed through?