John Kennedy actually said...
On and after August 29, 1963, those provisions of GATT and agreements supplementary thereto which have heretofore been proclaimed shall be applied as supplemented by the protocol relating to Spain of July 1, 1963 (identified in Part II(A) (1) of this proclamation),
Context
Proclamation 3553—Proclamation of Protocol for the Accession of Spain to the General Agreement on Tariffs and Trade
09/05/1963