John Kennedy actually said...
As President, I have determined that it is required or appropriate, on and after August 29, 1963, that those provisions of GATT and of agreements supplementary thereto which have heretofore been proclaimed be applied as supplemented by the protocol of July 1, 1963 (identified in paragraph (1) of this subpart).
Context
Proclamation 3553—Proclamation of Protocol for the Accession of Spain to the General Agreement on Tariffs and Trade
09/05/1963